Rainman: We experienced the same change in MPG using Shell midgrade. Can't say if it is the "Shell" or the higher Octane that retards the ignition level to accomodate the higher compression engines. Whatever it is the mileage is improved at all speeds with obvious max at 55-65 MPH (32 to 30MPG). 75-85 MPH drops to 29 & 27.5MPG that makes sense. All numbers with two passengers light luggage and fairly normal weather conditions. The computer on ours is very close to actual calculations so we are skipping that step. I believe the new 3.0/3.6L series V-6 prefers the higher octane fuels due to the higher compression ratios and the prom/computer program set up for mileage and nor low end torque/speed, but would be hard pressed to prove it with logic or math! 27.5 to 30+ on the highway is great for a 4300# car that is heavy (read mass) and safe by all measurements. In town is 16-18 with lots of variables so not consistent.
Your last trial was too short to conclude anything. But the refiners will love you with their higher margins on premium. I, also thought I was getting better mileage with mid grade at first (see earlier posts). But a few other tests lead me to doubt it. Also logic per below
I started to post a detailed analysis of gasoline energy but lost it before it went out . Bottom line, is that hi octane gas maybe up to 10% more dense (more lbs per gallon and more energy) but the energy per pound is 4-10% lower (lower hydrogen to carbon ratio of aromatics in hi test). So maybe, there is up to 6% more energy for a pure hydrocarbon fuel. But, a big factor is how much ethanol (high octane but about 1/3 less energy per pound relative to hydrocarbons)is added in your area. Also, your area (how cold) and winter vs summer count as butanes are added for easier starting and butane has somewhat lower energy per pound.
My 2011 CXS doesn't exhibit knock with 87 RON. Since 93 RON is about 25-30c/gal more (~8.3-10% at $3/US Gal), I conclude high test is a waste of money.
Q & Rainman: The new cars must be able to diagnose the engine performance with the feedback loop program and then adjusts the electronic timing advance up or down to use the octane and also keep the knock sensor happy. The 3.0/3.6L engines have relatively high compression ratios that would require 91/93 octane w/o the computer adjusting for feedback. The 3.0L engine in our 2010 CXL seems to run fine on regular (87) but wife feels it "likes" midgrade so it gets midgrade. We were told with previous cars that 91/93 was not good for cars that did not need it. The new engines we all have are definitely high performance given DOHC/DI/VVT & HP to displacement ratio. 250 - 285 HP for a 3.0 - 3.6L engine is pretty good. Bottom line: If the car runs well on regular octane and gets the mileage we use it and if the midgrade helps more than the cost we use that (or if the wife says to!)
Q, I read the general recommendations in the link you provided. Thanks. These are 7 years old and that's a long time span when it comes to computer operated systems. It also says to heed the owners manual. Mine requires 91 tier 1. Around here (Dertroit), I can choose Shell or Mobil. I started out running Regular from Marathon and BP. It wasn't until I had over 2k miles on my 2010 3.6L CXS that I learned it was intended to run Super (91).
I can't agree that if it doesn't knock, go with the lowest grade. There is still a financial calculation to be made. If MPG is up 20% on Super and the price of Super is only 10% over Regular, I'd be nuts to not to use Super. FYI, I have no engine knock on ANY brand or octane. Performance is identical in any normal driving I do or have done.
My 2011 CXL has 5,000 + miles on it. On the interstate with my cruise set at 72 MPH, for a 1 hour length of time, I achieved 27.5 MPG. In town it is more in the low 20's. To me this is decent gas mileage. If gas mileage was my main goal, I would have stuck with my 2010 Malibu which was getting 37 MPG in the same driving conditions. The ride and handling all rival my former 2006 DTS I had- and the LaCrosse handles curves and winding roads as well as the 2004 Pontiac GTP I had. I am completely satisfied with this car- many people can't believe it is a Buick. Before purchasing, I compared this to a Lexus 350 and Acura TL and the LaCrosse won hands down.
V-6. I just didn't feel that a 4 cylinder would do the job in the LaCrosse, as it did in my Malibu. Reading some of the earlier posts, I'm tempted to go to a higher octane fuel to increase MPG, as I always use regular unleaded.
Just so you know, the higher compression yields better efficiency. Before electronics, high octane was an obsolute must for high compression engines. They had no way to automatically retard the spark should knock or detonation occur. And the spark was usually advanced a bit more than regular engines. After the first concern of pollution was tackled, hydrocarbon emissions, they also started learning about noxious nitrogen compounds and many more tactics were employed to slow their production. Retarding the timing was one, hence poorer economy. Continuing fuel shortages has pushed technology into a very sophisticated engine. I knew hobbyists that installed fuel injection on their cars during the 60's so that part of the technology has been around. Electronic knock sensors may have been key in implementing today. Thus we now have high compression engines again via direct injection, leading to better efficiencies and also cleaner burning. Using too low an octane will cause the ignition to retard to prevent engine damage. Sometimes I'm confused with GM newer engines. 3.0 & 3.1, 3.5 & 3.6, 3.8 & 3.9. But now that 6 speed trannys are widely available I don't doubt there will be newer engines built that take advantage of that shift range and the way most people drive to squeeze even more economy.
FYI, with todays electronics, if you hear knock you have a serious problem. The sensitivity of these systems is designed that you should never hear it. So the likely symptom that you will see is reduced MPG because the engine is being retarded to avoid the destructive knock.
Reviewing manual, it says OK to use 87 but likely lower performance. I think I will stick with premium or at least 89. Using Chevron and Shell. Had a slight red flag the other night. Quite cool and as I eased my foot into it it sounded like it coughed. It definitely lost power momentarily. And I was able to repeat until engine got warm.
Thanks for the info- maybe this is why I have experienced an infrequent clanking sound when starting my car after sitting for a time. The additional cost for higher octane fuel is a mindset I will have to change for even better performance.
There were three (3) engine choices in the 2010s. A 4 cyl, a 3.0L V6 and a 3.6L V6. Only the larger V6 has Premium gas recommended. I have the 3.6 in my CXS.
My CXS mileage is getting better all the time. On my last tank of gas my milage increased from 18 to 19.1 mpg in city driving using Shell 93 octane. On regular gas I used to get 16.3 mpg so I am not sure if it is the higher octane or because the car is now broken in and more efficient. I believe it is a combination of both but I don't think I'll ever go back to regular though.
Picked up my daughter at the airport yesterday and she was in love with my LaCrosse on the way home. Although she works for Enterprise she'd never seen the CXS as they only carry the base CX in their fleet. Nonetheless, she feels the CXS at over $40K with navigation and the option packages is a bit overpriced.
Agree with the breakin experience. The cars seem to smooth out with time & miles.We are going to either midgrade or Shell Premium with our 2010 CXL 3.0L. Runs great on regular but seems to do better MPG wise on both midgrade and 91/93 octane. The biggest factor is Ethanol. Alabama had no ethanol for a while and Shell without it was maximum mileage. 10% Ethanol reduces MPG by 2-3 MPG on the highway. Guess that was the government plan - to use more fuel by subsidizing Ethanol and by the way- raise the cost of animal feeds,pork,beef and corn products. Ethanol also hard on rubber products- esp. older cars so if more Ethanol is in store for us lookout! **Please excuse the rant**** Daughter's comment is right on loaded CXS price. Cadillac CTS in mid $30's seems like a better buy. Lacrosse in low mid 30's is a great buy with all the necessary goodies. Real buy seems to be Mailbu I-4 and Sonata 4 cylinder for overall cost, features, mileage and true value concept.
My recent experience driving to Far West Texas - Houston to Terlingua area: I-10 from Houston to San Antonio is mostly a non-cruise control area as too much traffic for safety. West Of SA it becomes a 80 mph posted zone. From SA to Ft. Stockton, using 93 octane Exxon and cruise at 80ish, I got 25 mpg in the CXS. I use Mobil One oil but otherwise nothing unusual. Tires balanced out at 37 psi after traveling. Locally in Terlingua it is 2-lanes and all gas tops at 91 octane, not tier one. Return trip on US 90, a 3 lane road posted at 75 and cruise at 73ish, the car got right at 33 mpg from Marathon to Del Rio on Shell 91. Oil was at 70% life at the start and 56% when returned - an important point IMO. Car had 2 large adults and a full trunk. Not bad~!
John178, I would like to look into this for you. I would also recommend continuing to work with the dealer so they can try to diagnose your vehicle and take care of your concerns. Please e-mail me with your complete contact information including a good number to reach you, VIN, current Mileage, and involved dealer. I look forward to your response. Christina GM Customer Service
I was by dealer today hoping to get trim piece popped into place before hitting road. They ordered new one instead. Conversation on mileage came up somehow and service writer said they do not even consider MPG complaints until after 5000 miles. Past experience shows that to likely be a real number. Grain prices are higher in this country than usual world market because of the quality including more of something called gluten, I think. But watch out because number one in his effort to create more trade promised the Chinese grain at over $1 less than current market. I have no idea what the fallout will be but likely more bankrupt farmers at least, or bailouts?
My 2010 CXS stickered at $39,740 but sold for $35,640. This car is very loaded ,, even more so than the $64,000 MB E350 it replaced. Further with my GM credit card points, I knocked another $1500 off..a total cap cost reduction of $5600. Net selling price was $34,140. The Caddy CTS is a dated design, at least as far as body styling goes. In many markets, the only comparison is with an AWD CTS because a Rear (only) drive car is hard to sell. In my opinion, the Lacrosse is priced right.
And on breakin, it does not say so in this manual but I remember other vehicles that said not to drive at a constant speed for long periods during breakin. I guess the concept would be good but goes totally against what many would intuitively do with the restriction on speed set as it is. That is unless you push it past that for the 5 minute intervals and then back off to some other speed.
My practice has been to avoid using cruise control for the first 1000 miles and absolutely no full throtle acceleration. In the first 500 miles. I baby it, then from 501-1000 I drive as normal with the above two caveats. Don't forget that brakes need a 500 mile break-in too. With a manual trans, there is an easy way to seat the piston rings around 500-1000 miles. Just warm up the engine and then accelerate a few times in fourth gear from a low speed. I think I read this in Car & Drtiver 20 years ago.
bwia: Too bad about the Homelink. My prior post with the "learn" button on the opener worked (finally) for us after many tries. Handy and it needs no batteries, so worth another try with the engineer kid in the car and you on the ladder. My wife desires everything to work perfectly soooooo...
Finally, my son-in-law got Homelink to work, and with that I am now totally satisfied with my CXS.
It might help with deciding to use regular, mid, or premium at a Shell fill-up. The link extolls the benefits of using V-Power (premium) over even the lower grades of Shell.
You don't think Shell's claims are self-serving? All the top tier fuel members make similar claims. Example: http://www.chevron.com/products/techron/chevwtech/ They'd all prefer all customers to use their most costly fuels, necessary or not. So would their shareholders.
Likely they are, as well as others. My point was that they claim their premium contains extra amounts of additives, more than their other grades that still meet tier one. I saw no such claim on Chevron site, but when is clean clean enough? Chevron has had Tecron for at least 20 years and they claim nitrogen enriched. Unless they changed its formulation recently, maybe they were ahead of the rest. Makes me wonder if Shell is buying additive from Chevron?
Daughter has truck that she has been ignoring for many years. I got involved when a busted thermostat housing surfaced at 185K miles. Actually a couple of months earlier because she had been driving for at least 6 months with check engine and gas cap lights. I fixed the evap air leak and EGR code problems and gave her a list of needs. I noticed it was idling rather rough after full coolant system work and seemed to not be quite right when cruising around 50MPH. I learned her gas buying was whatever is cheapest. Not having expensive computer diagnostic I had to work with what clues I had, EGR was non-functional for at least 6 months, cheap gas, prematurely dirty oil, and that plugs and wires were done only a couple of years earlier. To be on safe side and maybe clean up some of the internal gunk I used oil known for its cleaning ability and factory filter which was much larger than that quick change place. Told her to watch oil changing at every fill and hope it does what it can. Pulled sparkplug. OMG, it must have been shade tree mechanic. No silicone so boots release from plug. No anti-seize on threads and plugs were very difficult to remove. Also they were the wrong plug. I had only pulled one which showed no wear but because of the above I decided they needed changing. I put it back in so I could work on a bit more cleaning without damaging new plugs. Ran most of a can of GM intake cleaner through it followed by Seafoam. Found excess oil around PCV valve and changed because I'd bet it was original one. Proceeded with sparkplug change. Oddly four of them showed extreme wear, none platinum or other high mileage type. The two with no wear were paired with two that had wear. I find this odd since this is a system where two fire simultaneously. What gives? Also replaced O2 sensors hoping to optimize a bit when it went to closed loop although rough symptoms showed in open loop. Both idler pulley bearings were also going and replaced pulleys. Test drive showed drastic improvement. Shifting became more precise with mild acceleration. I think the computer was having a hard time determining if the proper amount of torque was present for shifting because of weak running engine as it tried to lean out properly. Also the engine was much quieter as well as smoother. It still seems to have idle in neutral issue. I do not have equipment to reset computer so it may take time to relearn what is needed at idle or it may be a quirk of this engine trying to lean as much as possible and constantly being in the hunt for that spot. Or maybe it is time to get rid of those non-OE plug wires. And final instruction to her was start using tier one fuels, ONLY. Add bottle of Techron to first tank, the one for cleaning up system, the most expensive version. I am quite certain her husband got it wrong and used the one for cleaning injectors only. So to avoid confusion I asked her to fill with Shell Premium next time and hope it finishes any cleaning necessary. Sorry that I'm going into another vehicle but it has valid points. Be careful who does your work Use OE parts unless you have a really good reason not to. Pay attention to the fuel you use. Try to learn of recalls and TSB's on your own. If she had they would have replaced the first and second planetary gear sets in the transmission for the whirring sound they make until 100K, if she had complained. It would now cost her a couple of thousand. And check what parts your dealer is using. Likely safe under warranty because I think they have to return parts for credit. AFAIK, dealer service is not bound to use OE parts only. I have been in the parts area when other distributors were dropping off parts. And on one of my previous vehicles there were numerous posts about that Northstar engine not liking aftermarket parts, even something as simple as sparkplugs.
I have had intermittant (one in ten starts) clanging IMMEDIATELY upon starting....when I used non tier 1 Regular gas. With Shell Premium. I haven't heard it in the last twenty five starts. Keeping my fingers crossed. My guess is that the computer checking the knock sensor takes a second to come online after a start thus the timing is not yet retarded. In daily driving, there is no knock and performance seems normal. Gas mileage is better with Premium and the cost difference does not exceed the gain..so Premium it is in my 2010 3.6L
Too bad dealers don't have the good sense to ask about fuel when they hear this clanging compalint. One guy even had his exhaust system changed. Probably a coincidence. Maybe the dealer felt bad after the third trip and filled his tank for him...with better gas!
I would bet not. I have had the clang as well, but not in the past couple of weeks. I have heard spark knock and the sound I've heard is definitely not spark knock. If this sound was coming from inside the engine it would be destructive. Like a piston hitting a valve stuck open or worse. I won't rule out the release of the starter mechanism since it occurs at precisely the moment start occurs. And if related to that it could tear up the ring gear on the torque convertor. That would be horrible news since it would need tranny pulled.
I agree it is not likely related to gasoline octane/pre-ignition knock. My clang has diminished in occurrence but still happens. It seems related to outside cold temperature and rapid changes in same My dealer has replaced the long piece of the exhaust from the muffler to the front pipe for another owner which worked. He ordered same for me, My guess is its tied in to design/hanging of the pipe and rapid heat-up due to exhaust gas, expansion of pipe and interplay with pipe supports.
All seems possible at this point. It would seem to have to be near the front that the issue is. Since it happens so immediate upon start it seems to be reaching that it is related to heating. I'm sure you could grab pipe at the front, cold of course, and have someone start engine and it would be a few seconds before it got hot. That is not to say it might be related to temperature differential, the ambient being colder than normal. Does yours do it at the very moment engine starts? That is why I question that the starter may be involved. I do not know how this automatic start is set up but it could be the power to it is killed the moment engine RPM reaches just the point of running. And an improper release of the starter gear could be involved. Sometimes the starter motor has to be shimmed to acheive proper meshing of the gears. Improper mesh if not close enough could cause premature wear. Too close could cause binding resulting in late release or even no release. I hope I'm shooting in the wrong area but bring it to attention because the consequences could be far worse than just noise from exhaust pipe. And the down the road repairs would be far more expensive. If I can get at it, I will mark starter bolts to make sure they don't tamper with that and then neglect to tell me. As said, damaged gears could be major down the road even if shimming or adjusting does the immediate fix. BTW, starter is not part of powertrain coverage and not sure what they would say if starter gear damages ring gear on torque convertor. Has it come back on those who have had pipe change? Is it possible something was moved, loosened, retightened, etc. during the work, other than the exhaust itself? How much of it from the front was changed? Did it include the pre-converter right off the exhaust manifold? Possibly a defective weld in the system such as where pipes join other components or the seams on the converter. From what I've read that first one lights off almost immediately. That is, it is hot enough as soon as the engine starts to function unlike the ones further downstream.
Sorry, I have to ask again: When are you getting rid of your CXS? All your problems and suppositions of causes with their possible implications of more problems down the line sound like paranoia and must keep you totally awake each and every night. If your LaCrosse is presenting so many problems for you, why not trade it in for another Malibu? You seem to have been more satisfied with it.
Sit back and enjoy the ride. I do.
If I had as many issues and suspected problems as you are having with yours, I'd be at the dealer's every day looking for "lemon law" rectification.
Yes, I must admit it happens soon after I press the start button, But it rarely 'clangs' after a start in warmer weather or on a re-start after a recent running. Your note re:starter motor possibilities will be covered with service when I bring it in and before the exhaust system work.
Yesterday I went to the New England International auto show and I was impressed by all the new cars and SUVs. But I was very surprised to see how dated the Lacrosse and Malibu already look. BTW, the 2012 e-Lacrosse looks the same as the current version.
My favorites: Infiniti M56X, the seats are the best I've sat in and everything is just well laid out. The exterior styling is forgettable though. Lincoln MKS, wow! Big, powerful, refined and full of technology...it even reads text messages. Jeep Grand Cherokee--without a doubt, the best designed and refined SUV out there. The fit and finish and quality of materials are beyond anything Chrysler, or for that matter any manufacture has offered before.
Buzz: Nissan Leaf -- smaller than expected, the car was locked so we could not touch the interior instruments or surface material quality. Nice cockpit and well laid-out though. Chevy volt -- looks good from a distance as we couldn't get near enough to touch it. CTS-V -- I saw middle age men salivating over themselves Camaro -- In lime green it raised the testosterone level of teen boys about 20-fold Kia Optima -- best new exterior styling this year. The proportions look perfect
Disappointments: Equus -- looks lethargic, dated styling inside and out. High quality materials on door and seating surfaces. Honda and Lexus -- nothing new, generic styling, in short boring cars. Low gas mileage on most vehicles, 17/24 mpg seemed to be the norm
Surprises: Such little attention the Buick brand received, not even the Regal raised an eyebrow. Very large crowd at the 5-day show, although we are supposed to be in a recession. Oops! I forgot, the recession is over.
And under “surprises” I forgot to mention that Hyundai had the most impressive display and line-up of vehicles. It has emerged as a top manufacturer with admirable styling and dependable vehicles competing in every segment. From the entry level Accent to the Elentra (new and full with standard features) to the hybrid Sonata to the mid-luxury Genesis sedan/Coupe and to the ultimate in luxury the Equus. In 20 short years Hyundai has turned the auto industry upside down.
I am now past twenty-some starts without a clang. It is coincident with a switch to Shell Premium. I previously had it happen about 1 in 8 starts in ALL temperature, both ambient and engine, conditions.
The only "clang" I've ever heard from my CXS was once during cool-down in a not-too-cool garage with about 100 miles on the odometer. Nothing since then either at start-up or cooling even though we've had temps in teens & 20s. I'm now at about 2300 miles.
FWIW, I checked my oil yesterday and it looks really clean and up to the top, even after my long road trip. Rings must be seating pretty well. Had the car now almost 2 mos.
Bob: Totally agree with your comment on excessive worry over a collection of expendable parts on a platform called a "car" that is a tool to get you through the day and the needs of life - not the all consuming purpose of life. The Lacrosse is a great assembly of parts and design team efforts - THANK YOU Bob Lutz- before the phone guys at new GM marginalized him for excessive knowledge of the car business that made the outsiders look out of touch. Lacrosse, Malibu, CTS-V, SRX, Regal (Insignia clone) and other decisions were made years before the Chapter XI filing and the sacking of Wagoner and his team of old GM insiders that were stuck in the push model of the past past. Bob Lutz pushed for and got support for competitive designs that now sell well for GM. Sit back and enjoy is good advice for all of us. We s/b thankful to be able to afford a new car in these difficult times. Happy Holidays to all on this great board with VERY useful information on our cars.
Winter is here and my heater is working overtime. I use the auto setting to set the temperature at 73 but the AC light is still on. My question: in this frigid weather, is the AC really ON (i.e. the compressor) and if so, how can it heat and cool the car at the same time. I know in the defrost mode the AC helps to clear the fog up quickly but in the heating mode I don't see why it should be on.
Your AC most certainly cuts off at 50 degrees F or so to protect the system. The light probably indicates it's enabled as far as the electrical control unit thinks but the compressor is most likely off.
If you are comfortable, you can open you hood. Then sit in the driver seat and start the motor. After it runs a minute or so, turn the AC from OFF to the ON position where the AC light is turned on. If the compressor is turning on, you'll hear a metallic soft "thunk" as it engages.
Or if you know where the compressor is on the belt system, you can look at the center part of the pulley while the engine is running. If it's turning with the outside of the hub that the belt wraps around, the compressor is engaged. If the center is stationary, the compressor is not pumping freon.
The owners manual section "Climate Controls" explains the operation of all the control buttons. The A/C button is on when in auto mode. If you manually change the setting by pushing the A/C button the light goes out and the A/C compressor will not run. The auto mode allows the system to automatically detect humidity and/or the need to defrost moisture from the front window so keeping it in auto mode allows for these function to operate. Best to read the manual since the options are multi-variable. We turn off the A/C button when the windshield is clear and we want to add heat to the interior and maximize mileage (read no A/C compressor running). The unit is "smart" so overriding and running manually is like having an uniformed boss at work- the unit becomes disfunctional. Again, best to read the manual IMO.
Thanks crankee and thanks imidazol97 for the image. Intuitively I know the AC is not supposed to be engaged below 50 degrees. But with the blue AC light on I thought perhaps the heater was not overriding the AC.
BTW, it just hit me. The improvement in my gas mileage is due to the compressor being turned off during the cold weather rather than the higher 93 octane or purported engine break-in.
I am about to buy the 2011 Buick Lacrosse CXL, comes with All wheel drive package. I live near the Canadian border (Quebec) and the weather gets nasty. The dealer tells me I don't need winter tires, because of the AWD. Is this true? I will have kids in the car and safety is my top priority.
dunno about the AWD but: I own a 05 LaCrosse and was surprised to find out it cannot be outfitted with chains. Per the owner's manual, this is due to the tire size and not having enough clearance in wheelwells. As to the AWD: suggest you do your own research. just seems to me that having "normal" tires on the vehicle as opposed to "mud/snow" traction tires, would make a BIG difference in the ice/snow. Ask your "dealer" to show you the tires on his/her vehicle!
If you intend to keep the car several years, they are a good investment. You probably need all four wheels to be safe. I use "all season" mud & snow in Detroit. It covers 95% of all conditions. When it doesn't, I stay home.
A lot depends on the roads and their maintenance. Consider how remote the roads are you travel. For me, help is usually nearby.
Unless you are a first responder you do not need snow tires as your Lacrosse comes with all season tires installed. I live in Boston which is the US's snowiest big city yet I've never used dedicated snow tires because the roads are plowed, sanded and well maintained. So unless you are someone who has to be on the road before the snow plows you will be just fine with regular tires, AWD or not.
By the way, is it me or the new setup that does not allow cutting and pasting? At the beta stage all features appeared to have worked flawlessly but now I am noticing several hicups including the inability to edit a post.
Well folks I am at 3,965 miles and quickly approaching the 4K mile mark with zero reportable conditions and I still have a big grin on my face every time I push the start button.
My gas mileage has deterioated. On my previous tankful I got 20.91 mpg but today, with my most recent fill-up with Shell octane 93 V-Power I got a disappointing 17.5 mpg. It is the true the weather has been unseasonably cold but that is a big drop.
And today I had a pleasant surprise. I took my CXS to a Chevy dealership because my tire pressure had dropped to 32 psi in all tires (yes the weather is really cold out there). Almost everyone in the service department rushed up to take a look and sit in my car. Their reactions were unanimous..."wow what a great car!"
Sorry for the boring update but there is nothing to report really. The car just works flawlessly with the heater keeping my cabin at a comfortable 73 degrees. How sweet. BTW, after five months I'm still having issues with parallel parking. The combination of the high rear deck, sensor and back-up camera can be a little disorienting at times. Nonetheless, a great car and I have no regrets switching from the Avalon to the CXS.
Comments
27.5 to 30+ on the highway is great for a 4300# car that is heavy (read mass) and safe by all measurements. In town is 16-18 with lots of variables so not consistent.
I started to post a detailed analysis of gasoline energy but lost it before it went out
Also see:
http://www.ftc.gov/bcp/edu/pubs/consumer/autos/aut12.shtm
which advises higher octane only if your engine knocks significantly.
My 2011 CXS doesn't exhibit knock with 87 RON. Since 93 RON is about 25-30c/gal more (~8.3-10% at $3/US Gal), I conclude high test is a waste of money.
Bottom line: If the car runs well on regular octane and gets the mileage we use it and if the midgrade helps more than the cost we use that (or if the wife says to!)
2017 Cadillac ATS Performance Premium 3.6
I can't agree that if it doesn't knock, go with the lowest grade. There is still a financial calculation to be made. If MPG is up 20% on Super and the price of Super is only 10% over Regular, I'd be nuts to not to use Super. FYI, I have no engine knock on ANY brand or octane. Performance is identical in any normal driving I do or have done.
After the first concern of pollution was tackled, hydrocarbon emissions, they also started learning about noxious nitrogen compounds and many more tactics were employed to slow their production. Retarding the timing was one, hence poorer economy.
Continuing fuel shortages has pushed technology into a very sophisticated engine.
I knew hobbyists that installed fuel injection on their cars during the 60's so that part of the technology has been around. Electronic knock sensors may have been key in implementing today.
Thus we now have high compression engines again via direct injection, leading to better efficiencies and also cleaner burning.
Using too low an octane will cause the ignition to retard to prevent engine damage.
Sometimes I'm confused with GM newer engines. 3.0 & 3.1, 3.5 & 3.6, 3.8 & 3.9. But now that 6 speed trannys are widely available I don't doubt there will be newer engines built that take advantage of that shift range and the way most people drive to squeeze even more economy.
Had a slight red flag the other night. Quite cool and as I eased my foot into it it sounded like it coughed. It definitely lost power momentarily. And I was able to repeat until engine got warm.
Picked up my daughter at the airport yesterday and she was in love with my LaCrosse on the way home. Although she works for Enterprise she'd never seen the CXS as they only carry the base CX in their fleet. Nonetheless, she feels the CXS at over $40K with navigation and the option packages is a bit overpriced.
Daughter's comment is right on loaded CXS price. Cadillac CTS in mid $30's seems like a better buy. Lacrosse in low mid 30's is a great buy with all the necessary goodies. Real buy seems to be Mailbu I-4 and Sonata 4 cylinder for overall cost, features, mileage and true value concept.
I-10 from Houston to San Antonio is mostly a non-cruise control area as too much traffic for safety. West Of SA it becomes a 80 mph posted zone.
From SA to Ft. Stockton, using 93 octane Exxon and cruise at 80ish, I got 25 mpg in the CXS. I use Mobil One oil but otherwise nothing unusual. Tires balanced out at 37 psi after traveling.
Locally in Terlingua it is 2-lanes and all gas tops at 91 octane, not tier one.
Return trip on US 90, a 3 lane road posted at 75 and cruise at 73ish, the car got right at 33 mpg from Marathon to Del Rio on Shell 91. Oil was at 70% life at the start and 56% when returned - an important point IMO.
Car had 2 large adults and a full trunk. Not bad~!
I would like to look into this for you. I would also recommend continuing to work with the dealer so they can try to diagnose your vehicle and take care of your concerns. Please e-mail me with your complete contact information including a good number to reach you, VIN, current Mileage, and involved dealer. I look forward to your response.
Christina
GM Customer Service
Conversation on mileage came up somehow and service writer said they do not even consider MPG complaints until after 5000 miles. Past experience shows that to likely be a real number.
Grain prices are higher in this country than usual world market because of the quality including more of something called gluten, I think. But watch out because number one in his effort to create more trade promised the Chinese grain at over $1 less than current market. I have no idea what the fallout will be but likely more bankrupt farmers at least, or bailouts?
Finally, my son-in-law got Homelink to work, and with that I am now totally satisfied with my CXS.
I will be at my Dad's next week and will give it a try then, especially with zero windchill.
It turns out only the premium has what they call V-Power. All grades do meet tier one though.
http://www.shell.us/home/content/usa/products_services/on_the_road/fuels/shell_v- power/about_vpower/
It might help with deciding to use regular, mid, or premium at a Shell fill-up. The link extolls the benefits of using V-Power (premium) over even the lower grades of Shell.
My point was that they claim their premium contains extra amounts of additives, more than their other grades that still meet tier one. I saw no such claim on Chevron site, but when is clean clean enough?
Chevron has had Tecron for at least 20 years and they claim nitrogen enriched. Unless they changed its formulation recently, maybe they were ahead of the rest. Makes me wonder if Shell is buying additive from Chevron?
Daughter has truck that she has been ignoring for many years. I got involved when a busted thermostat housing surfaced at 185K miles. Actually a couple of months earlier because she had been driving for at least 6 months with check engine and gas cap lights. I fixed the evap air leak and EGR code problems and gave her a list of needs.
I noticed it was idling rather rough after full coolant system work and seemed to not be quite right when cruising around 50MPH. I learned her gas buying was whatever is cheapest. Not having expensive computer diagnostic I had to work with what clues I had, EGR was non-functional for at least 6 months, cheap gas, prematurely dirty oil, and that plugs and wires were done only a couple of years earlier.
To be on safe side and maybe clean up some of the internal gunk I used oil known for its cleaning ability and factory filter which was much larger than that quick change place. Told her to watch oil changing at every fill and hope it does what it can.
Pulled sparkplug. OMG, it must have been shade tree mechanic. No silicone so boots release from plug. No anti-seize on threads and plugs were very difficult to remove. Also they were the wrong plug.
I had only pulled one which showed no wear but because of the above I decided they needed changing. I put it back in so I could work on a bit more cleaning without damaging new plugs.
Ran most of a can of GM intake cleaner through it followed by Seafoam. Found excess oil around PCV valve and changed because I'd bet it was original one.
Proceeded with sparkplug change. Oddly four of them showed extreme wear, none platinum or other high mileage type. The two with no wear were paired with two that had wear.
I find this odd since this is a system where two fire simultaneously. What gives?
Also replaced O2 sensors hoping to optimize a bit when it went to closed loop although rough symptoms showed in open loop.
Both idler pulley bearings were also going and replaced pulleys.
Test drive showed drastic improvement. Shifting became more precise with mild acceleration. I think the computer was having a hard time determining if the proper amount of torque was present for shifting because of weak running engine as it tried to lean out properly. Also the engine was much quieter as well as smoother.
It still seems to have idle in neutral issue. I do not have equipment to reset computer so it may take time to relearn what is needed at idle or it may be a quirk of this engine trying to lean as much as possible and constantly being in the hunt for that spot. Or maybe it is time to get rid of those non-OE plug wires.
And final instruction to her was start using tier one fuels, ONLY. Add bottle of Techron to first tank, the one for cleaning up system, the most expensive version. I am quite certain her husband got it wrong and used the one for cleaning injectors only. So to avoid confusion I asked her to fill with Shell Premium next time and hope it finishes any cleaning necessary.
Sorry that I'm going into another vehicle but it has valid points.
Be careful who does your work
Use OE parts unless you have a really good reason not to.
Pay attention to the fuel you use.
Try to learn of recalls and TSB's on your own. If she had they would have replaced the first and second planetary gear sets in the transmission for the whirring sound they make until 100K, if she had complained. It would now cost her a couple of thousand.
And check what parts your dealer is using. Likely safe under warranty because I think they have to return parts for credit. AFAIK, dealer service is not bound to use OE parts only. I have been in the parts area when other distributors were dropping off parts.
And on one of my previous vehicles there were numerous posts about that Northstar engine not liking aftermarket parts, even something as simple as sparkplugs.
I have had intermittant (one in ten starts) clanging IMMEDIATELY upon starting....when I used non tier 1 Regular gas. With Shell Premium. I haven't heard it in the last twenty five starts. Keeping my fingers crossed. My guess is that the computer checking the knock sensor takes a second to come online after a start thus the timing is not yet retarded. In daily driving, there is no knock and performance seems normal. Gas mileage is better with Premium and the cost difference does not exceed the gain..so Premium it is in my 2010 3.6L
Too bad dealers don't have the good sense to ask about fuel when they hear this clanging compalint. One guy even had his exhaust system changed. Probably a coincidence. Maybe the dealer felt bad after the third trip and filled his tank for him...with better gas!
I won't rule out the release of the starter mechanism since it occurs at precisely the moment start occurs. And if related to that it could tear up the ring gear on the torque convertor. That would be horrible news since it would need tranny pulled.
Does yours do it at the very moment engine starts? That is why I question that the starter may be involved. I do not know how this automatic start is set up but it could be the power to it is killed the moment engine RPM reaches just the point of running. And an improper release of the starter gear could be involved. Sometimes the starter motor has to be shimmed to acheive proper meshing of the gears. Improper mesh if not close enough could cause premature wear. Too close could cause binding resulting in late release or even no release. I hope I'm shooting in the wrong area but bring it to attention because the consequences could be far worse than just noise from exhaust pipe. And the down the road repairs would be far more expensive. If I can get at it, I will mark starter bolts to make sure they don't tamper with that and then neglect to tell me. As said, damaged gears could be major down the road even if shimming or adjusting does the immediate fix. BTW, starter is not part of powertrain coverage and not sure what they would say if starter gear damages ring gear on torque convertor.
Has it come back on those who have had pipe change?
Is it possible something was moved, loosened, retightened, etc. during the work, other than the exhaust itself?
How much of it from the front was changed? Did it include the pre-converter right off the exhaust manifold? Possibly a defective weld in the system such as where pipes join other components or the seams on the converter. From what I've read that first one lights off almost immediately. That is, it is hot enough as soon as the engine starts to function unlike the ones further downstream.
Sit back and enjoy the ride. I do.
If I had as many issues and suspected problems as you are having with yours, I'd be at the dealer's every day looking for "lemon law" rectification.
My favorites:
Infiniti M56X, the seats are the best I've sat in and everything is just well laid out. The exterior styling is forgettable though.
Lincoln MKS, wow! Big, powerful, refined and full of technology...it even reads text messages.
Jeep Grand Cherokee--without a doubt, the best designed and refined SUV out there. The fit and finish and quality of materials are beyond anything Chrysler, or for that matter any manufacture has offered before.
Buzz:
Nissan Leaf -- smaller than expected, the car was locked so we could not touch the interior instruments or surface material quality. Nice cockpit and well laid-out though.
Chevy volt -- looks good from a distance as we couldn't get near enough to touch it.
CTS-V -- I saw middle age men salivating over themselves
Camaro -- In lime green it raised the testosterone level of teen boys about 20-fold
Kia Optima -- best new exterior styling this year. The proportions look perfect
Disappointments:
Equus -- looks lethargic, dated styling inside and out. High quality materials on door and seating surfaces.
Honda and Lexus -- nothing new, generic styling, in short boring cars.
Low gas mileage on most vehicles, 17/24 mpg seemed to be the norm
Surprises:
Such little attention the Buick brand received, not even the Regal raised an eyebrow.
Very large crowd at the 5-day show, although we are supposed to be in a recession. Oops! I forgot, the recession is over.
FWIW, I checked my oil yesterday and it looks really clean and up to the top, even after my long road trip. Rings must be seating pretty well. Had the car now almost 2 mos.
The Lacrosse is a great assembly of parts and design team efforts - THANK YOU Bob Lutz- before the phone guys at new GM marginalized him for excessive knowledge of the car business that made the outsiders look out of touch. Lacrosse, Malibu, CTS-V, SRX, Regal (Insignia clone) and other decisions were made years before the Chapter XI filing and the sacking of Wagoner and his team of old GM insiders that were stuck in the push model of the past past. Bob Lutz pushed for and got support for competitive designs that now sell well for GM.
Sit back and enjoy is good advice for all of us. We s/b thankful to be able to afford a new car in these difficult times.
Happy Holidays to all on this great board with VERY useful information on our cars.
If you are comfortable, you can open you hood. Then sit in the driver seat and start the motor. After it runs a minute or so, turn the AC from OFF to the ON position where the AC light is turned on. If the compressor is turning on, you'll hear a metallic soft "thunk" as it engages.
Or if you know where the compressor is on the belt system, you can look at the center part of the pulley while the engine is running. If it's turning with the outside of the hub that the belt wraps around, the compressor is engaged. If the center is stationary, the compressor is not pumping freon.
2014 Malibu 2LT, 2015 Cruze 2LT,
BTW, it just hit me. The improvement in my gas mileage is due to the compressor being turned off during the cold weather rather than the higher 93 octane or purported engine break-in.
As to the AWD: suggest you do your own research. just seems to me that having "normal" tires on the vehicle as opposed to "mud/snow" traction tires, would make a BIG difference in the ice/snow. Ask your "dealer" to show you the tires on his/her vehicle!
A lot depends on the roads and their maintenance. Consider how remote the roads are you travel. For me, help is usually nearby.
By the way, is it me or the new setup that does not allow cutting and pasting? At the beta stage all features appeared to have worked flawlessly but now I am noticing several hicups including the inability to edit a post.
My gas mileage has deterioated. On my previous tankful I got 20.91 mpg but today, with my most recent fill-up with Shell octane 93 V-Power I got a disappointing 17.5 mpg. It is the true the weather has been unseasonably cold but that is a big drop.
And today I had a pleasant surprise. I took my CXS to a Chevy dealership because my tire pressure had dropped to 32 psi in all tires (yes the weather is really cold out there). Almost everyone in the service department rushed up to take a look and sit in my car. Their reactions were unanimous..."wow what a great car!"
Sorry for the boring update but there is nothing to report really. The car just works flawlessly with the heater keeping my cabin at a comfortable 73 degrees. How sweet. BTW, after five months I'm still having issues with parallel parking. The combination of the high rear deck, sensor and back-up camera can be a little disorienting at times. Nonetheless, a great car and I have no regrets switching from the Avalon to the CXS.