What about fuel types & gas mileage?

corvette · October 2004

Does anyone have proof that there are better inject maintenance productws in premium?

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Shell and Chevron readily admit so. Shell's V-Power is only in their premium grade, and Chevron says that their premium fuel contains more Techron than the lower grades.

corvette · October 2004

If you're talking about a car designed for regular, no. If it advanced the timing when burning premium fuel, it would produce more power, but we know that cars designed for regular don't make more power with premium.

stever · October 2004

So how often is the timing set? It is adjusted (or verified) with every camshaft rotation? The computer sensor must be checking it periodically, unlike the old days when you physically moved the distributor cap or whatever with a timing light hooked up.

Top Tier Gas anyone?

kgbkahnk "Chevy Trailblazer, GMC Envoy, Oldsmobile Bravada" Oct 27, 2004 1:38pm

Steve, Host

Mr_Shiftright · October 2004

Well I wouldn't buy premium fuel just because it had more techron in it, because my car doesn't need techron 24/7. I can just "dose it" once in a while if I choose, and probably with something a bit stronger than what's in the gas.

davidkeith37 · November 2004

I have some suggestions if you really want to get into the question of octane and timing. There is a $100.00 instrument called a ScanGuage, see at Scanguage.com which among many other functions reads out ignition timing, %load, rpm, gpm, mpg,and etc. You will need a good note taker, a good slope to load the engine, a statistician to to help design the test and make sense of the numbers, a way to cancel out the ambient differences between runs, a way to adequately empty the tank between grades of fuel, and so and so forth. If anyone does carry out this I do hope they post the results here for all to see. As for me I, most likely, will use 87 (grade) and check the ignition timing on a moderate uphill slope I routinely do in my 2004 Hyundai Santa Fe 2.4 L MT. If it is suddenly and significantly retarded from the usual average for that mile post I will assume I have a load of bad gas and will fill up as soon as convenient to dilute the bad with good gas.

gregoryc1 · November 2004

You should be running some type of fuel additive on an "on going basis", because deposits build up over time in the upper cylinder area of the engines. (Valves & Piston Rings / Lands & Injectors). Letting these deposits build up, and then trying to remove them is not productive in terms of engine performance and fuel mileage. In addition, the time it takes for an injector to "open" is critical to the total performance of the engine. Anything, that slows down that "opening time" will create performance problems. Both the interior and exterior of the fuel injectors should to be clean, and the components must operate in a smooth fashion. In addition, deposits on the back of the valves will absorb fuel, thus creating a lean mixture in the cylinders. A lean mixture causes additional heat, and engine damage. Deposits behind the piston rings locks the rings into the lands of the piston, causing compression issues and possible "blow by". In the case of "blow by", the PCV system will be overloaded, and engine oil consumption will increase. (Some PT Cruisers seem to have a issue like this in some of their engines as they accumulate some mileage). I suspect that the cause of this oil consumption problem is either deposits in the combustion chamber, or the rings were installed up-side-down on some of these engines at the factory. It does not show up on all the PT cruiser engines, so there must be some special circumstances on the oil buning engines. Anyway, deposit control is an important issue for the internal combustion engine, and it should not be neglected as part of a preventive maintenance program.

Mr_Shiftright · November 2004

Well possibly but you know I haven't had a bad injector on a gasoline engine in any car I have ever owned, nor has cylinder head removal shown any significant depositing. So I'm gonna stick with what works, and just dose the car every now and then.

Of course, I don't disagree that poorly engineered engines or defective running will create problems--that's certainly possible.

But my additive is quite expensive and I'm certainly not going to put it in very often...that would cost me over $200 a year and I don't see the cost benefit from my own past experience. YRMV.

shipo · November 2004

I fail to understand how you can continue to post controversial factoids such as the ones in your most recent post without ever, as in not even once, providing any references to supporting science. It's almost as if you enjoy being ridiculed and laughed at.

Specific to this latest bucket of bilge water:

Modern automotive fuel contains an additive package that is designed specifically to keep all of the components of the fuel system clean and in good working order for the life of the car AND all of the scavengers necessary to keep the combustion chamber and exhaust system clean and carbon free. Any engine that exhibits premature component failure and/or carbon deposits is either incorrectly fueled (as in using premium in a car designed for regular fuel), incorrectly operated, or a non-conforming engine (as in upside down rings or induction leaks). Disagree? I'm sure you do, however, you seem to have absolutely zero proof.

Regarding your silly statement, "A lean mixture causes additional heat, and engine damage." Oh really? Says who? If you look at the science, you will see that as the fuel/air mixture leans past stoichiometric, the combustion pressures DROP rather dramatically, and as a result so do the temperatures. As you continue to lean the mixture, the pressures and temperatures continue to drop, all of the way to the point where the mixture is too lean to sustain a flame front, and essentially fails to burn. How is that hot?

In the end, assuming an owner of any given late model car follows the manufacturers recommendations relative to fueling and maintenance, there should be no need whatsoever to add anything extra for the life of the car.

Best Regards,
Shipo

badgerfan · November 2004

Personally, I think one should add snake oil to your bilge water. This will keep your bilge from developing nasty deposits.

On the other hand, marvelous mysterious oil might work better yet...........

I've been buying the cheapest gas I can find for many years now, and put no additives in, and cannot remember the last time I have even had one misfire, rough idle or anything of the sort. Of course I don't drive Hondas. Maybe they need all these Wonders-in-a-Can to operate properly.

imidazol97 · November 2004

You need to provide proof for your statements.

Your posts toward gregoryc sound rude and arrogant, and you yoursefl provide no proof, only your own statements. He makes his statements; you make yours. Neither provide verifiable proof. It's your opinions. I read both and determine my own opinion.

If you disagree with someone's postings, politely reply or ignore them, please.

Personally I use Techron by Chevron. It does make a difference in the car's running after I use it. This is probably injector cleaning having an effect. I don't take my heads off to check for deposites so I don't know how residue is left inside the combustion chambers.

shipo · November 2004

Hmmm, rude and arrogant, well, I suppose that is a matter of conjecture, having said that, I will address that a little later in this post.

I attempt to provide references that support the beliefs that I state, which were developed from considerable research, wherever and whenever I can. That I cannot offer "Proofs" to disprove the factoids that gregoryc posts is rather difficult. It would be like my saying that Marvel Mystery Oil, when taken orally as a prophylactic measure, will cure zits. Then, when the guaranteed outcry comes, I simply respond with, "Oh yeah! Prove that it doesn't." It is very difficult to prove a negative in that fashion. Why? Simple, because no competent scientist would spend the time, money and energy to prove something so silly.

So, are my posts rude and arrogant? Yes, I'm trying to get him mad enough to finally do a little research on his own, and then if he does find some supporting science, THEN we have something to talk about. Until then, it's like this:

G: "Lead in the form of TEL was used to lubricate valves"

S: "No, sorry G, but lead is not now, nor has it ever been used to lubricate valves. TEL is simply an octane enhancer/knock inhibitor."

G: "Go look it up."

S: "I did, here are 5 scientific links to the likes of Universities, NACA and the SAE that specifically state the TEL was developed as an octane enhancer, and that is what it is/was used for. Please note there is no reference to the lubricity value of TEL."

G: "Lead in the form of TEL was used to lubricate valves"

S: "Here we go again..."

Regarding Techron, there was a time when it was required by the manufacturer (BMW, any others?) for some cars to keep their fuel systems in peak condition. That time has passed as there are now international standards regarding the additive packages put in the fuel that we can currently buy. Said additive packages are specifically designed to keep the fuel systems of late model cars in peak operating condition for the life of the car. In the past I posted several links supporting that statement, and if pressed, I could come up with them again.

Regarding your use of Techron, a sampling of one does not a scientific study make. That said, I can turn right around and say that two of our three cars are virtually identical twins, the only difference being the 5 model years that separate them. So? Well, the older one, which has nearly 90K miles on it runs easily as well as the newer one. Not only that but it has consistently improved its fuel economy each year since new to the point where it is now getting on average about 3 more miles per gallon on the frequent NYC to Southern New Hampshire trip that I have been driving it on since it was new.

Is that scientific either? Nope, it is just as irrelevant, however, if I was to listen to the bilge that G plasters everywhere and anywhere he can, I would be lead to believe that the older car is ready for the scrap heap simply because I have never put in SuperXXX (fill in your favorite snake oil here) in the gas and oil, or used any other "preventative" measure beyond what the manufacturer recommends.

Maybe I'm missing something, however, when someone like G posts things that are controversial, and contrary to what the engineers who designed and built the engines in our cars have said, they need to substantiate their claims. Is that too much to ask? Yes, no?

Best Regards,
Shipo

badgerfan · November 2004

I've long since decided to read G's posts without challenging them, as life is too short. I will reply with humor tinged with a bit of satire only, as it is obvious to me that G is not going to change.

imidazol97 · November 2004

I did NOT say that my use of Techron was a scientific study. I gave my anecdotal example that its efficacy is good in my case.

shipo · November 2004

"I did NOT say that my use of Techron was a scientific study."

I'm sorry, my bad, I had no intention of implying such. ;-)

Best Regards,
Shipo

imidazol97 · November 2004

I read this note by ALCAN in the discussion OIl Change Fiascos about rings being locked from working properly!!!

alcan "Oil change/fiascos" Nov 25, 2004 6:27am

Mr_Shiftright · November 2004

I think Alcan's whole point was that these cars in particular were badly engineered, not that this is common in most modern cars. In other words, this isn't maintenance but rather a means of addressing (temporarily I fear) a defect. But if he wants to clarify that, by all means let's hear from him.

shipo · November 2004

I think that he did clarify the situation in this follow-up post:

alcan "Oil change/fiascos" Nov 25, 2004 11:58am

Best Regards,
Shipo

Mr_Shiftright · November 2004

Oh, I see that he does. I thought I remember reading something about the defective rings. That's interesting. Well then, in that case a gasoline additive isn't going to help you, but maybe an frequent oil changes would save your Saturn from this fate.

Old Volvos are notorious for a similar problem---wherein you get excellent compression readings on a basically worn out engine---because the compression rings are not affected but the oil rings are.

Compression tests alone can fool 'ya.

cablack · January 2005

Sorry for this somewhat regional question, but: what do you folks know about "winter gas" that they apparently sell in CA (in the winter, of course), if not in other states?

I have heard that it is oxygenated, which reduces pollution in older cars, but results in poorer gas mileage for everybody else. And so I've been assuming that my mileage will improve once spring rools around.

But I don't know for sure, so I'd love to hear what you folks know about it. Thanks!

marc55 · March 2005

I recently bought a 1998 Ford Ranger (127,000 miles from Bro-in-law) 3.0, auto, 4x4, 16 inch wheels and 410 rear end. I'm getting 12-13 mpg in city and I feel it should be closer to 16 in the city. I've installed: new plugs, wires, oil blow by valve, K&N air filter. Check engine light revealed a need for a new emission component (forgot name, sits atop engine and runs two tubes to emission pipe) and was replaced. No check engine lights aglow, and seems to run fine. Do I need a reality check to realize that a 410 rear end and 13 city mpg is as good as it gets or, need I explore other possibilities for possible problems? If so, any help would be appreciated.

shipo · March 2005

With the 4.10 gears, my bet is that you've got it as good as it's going to get. To take it one step further, I'm surprised that your mileage is as good as it is.

Best Regards,
Shipo

carcurious3 · March 2005

Can anyone tell me where I can find out how the weight in my car will affect my gas mileage? I am planning a 3300 mile trip and trying to figure if it would be more cost effective to mail mail my 200 pounds worth of belongings or bring them with me in the car.

shipo · March 2005

What kind of car? Can you fit the 200 pounds of stuff inside or will it be stored in a roof rack system?

If you can fit it inside, it is unlikely that you would notice the difference in your mileage unless you are driving a very small, very low powered car (and even then the difference in fuel mileage would no where near make up the cost of shipping). Consider this, 200 pounds is less weight that an extra passenger and a tank of gas.

Best Regards,
Shipo

john500 · March 2005

According to the website attached, a rule of thumb reduction in vehicle weight of 1 % reduces fuel consumption by 0.7 %. Assuming you own a 3000 pound car, 200 pounds represents 6.7 %(.7) = at most 5 % fuel consumption reduction. Therefore, if your gas mileage is 25 mpg, worst case scenario you would go down to 23.75 mpg.
3300 miles(1 gallon / 25 miles)($2/gal) = $264
3300 miles(1 gallon / 23.75 miles)($2/gal) = $277

As shipo indicated, it really depends on the car, however, I doubt that you could ship 200 pounds of freight for under $20 (rounded up for fluctuating gas prices).

http://www.titaniuminfogroup.co.uk/automotive.htm

husky92 · March 2005

Here in the northwest, Arco gas is inexplicably cheaper by about a 10 to 20 cents a gallon than anybody else. I've heard several people I know comment that they won't put that crap in their car, but I've never heard anything to substantiate that claim. I tend to go out of my way to use Arco gas generally, although most don't accept credit cards so it is less convenient. I suppose they are cheaper because they don't take credit cards, but I have found 1 Arco that does take them and they are still cheaper.

Isn't gasoline regulated. I mean, 87 octane is 87 octane right?

Mr_Shiftright · March 2005

You'll hear all kinds of anecdotal evidence pro and con, and I'm sure some of it really happened, but I have personally never ever chosen a particular gas station in decades of driving. I just shop price and put whatever the hose is offering into my tank wherever my gas warning light happens to light up. I've never once had a really bad experience--maybe I can recall a burp or two. Of course common sense tells us to probably pass on the gas station that has a broken sign swinging in the wind, huge cracks in the pavement and tumbleweed stuck to the RV trailer they're using for an office.

mcdaniel4 · March 2005

Hi. I have a Chevy Tahoe, 2004, which I love. However, a full tank costs about 50$ now vs 38-40$ last year. I like your thoughts on fuel, because I have been thinking about staying home as much as possible. I get around 14mpg around town, 17-18 highway. The size of the vehicle does have some safety factors. I was thinking about trying to figure out how I could go to a smaller car, like a Toyota Avalon, for the gas. I doubt they would want to trade for my car. I guess I'll just not worry about the gas prices. Per day, around town, it would be much cheaper than a cab.
Any thoughts?
PM

Mr_Shiftright · March 2005

When you're talkin' gas mileage, you really should focus NOT on miles per gallon but on GALLONAGE differences between two vehicles.

In other words, you say you get 18 mpg highway. Well if you buy a small car you might bump that up to 24. And you know, depending on how many miles you drive a year, that may not add up to many extra gallons per year. It's really only about 15 gallons per month.

So thinking gallons rather than MPG gives you a better handle on how significant switching vehicles might be.

For me for instance, to trade in my Porsche for a Toyota sedan would save me, per year, enough gallonage for two new car payments out of the twelve. That's not enough to motivate me.

imidazol97 · April 2005

I look at the total cost of ownership. I picked (again) a car with the 3800 engine that a few on a GM discussion here discount as old, pushrod technology. Well the 3600 pound car gets me 22.5 in around town mileage with my wife short-tripping it to 33 on interstate driving. It's a larger heavier car, roomy, and smooth.

When I traded for my second LeSabre, I couldn't find a way to trade the older LeSabre for a smaller car for better mileage. Having two LeSabres seemed overkill. I already owned the '93 and it got good mileage and I would have paid more to have less car with slightly better mileage if I traded it.

Now that gas prices here are solidly above $2.00 I really notice only some increase in total gas cost. I make a few less trips by consolidating small trips and probably save a lot I used to waste. I certainly am getting better mileage than the SUV owners who drive a long commute at 15 mpg. And many still haven't slowed down to save the extra gallons they could save by driving 62 instead of 75-80 between Dayton/Cincinnati. I realize some people driving a pickup because it's a work vehicle.

silkworm · April 2005

This is my first post, so please be gentle...

I have a 2000 Passat GLS and a 2004 Acura MDX. Manuals for both cars say that only premium gasoline should be used (91 or 93 octanes or better, can't remember which). However, I have heard that premium fuel is recommended for new cars, so switching to lower grades will not damage anything as the car ages. However, I have also heard that older cars benefit from premium gasoline. I need someone to set the story straight. With today's gas prices, it would be great if I could switch to regular gasoline. We only put about 500 miles per month in each vehicle, so this is not a critical thing, but it would still help. Thanks!

Mr_Shiftright · April 2005

Okay. Yes, you can run a lower grade of fuel and your car's computer will adjust for that; however, you may (or may not) notice a degradation of performance, i.e. acceleration.

The age of a car has nothing to do with its octane requirements. Either your car's engine is built and designed for a certain grade of fuel or it isn't. You can't "treat" your car to a higher octane than it was designed for. That is wasting money. But you can use a lower octane as long as you can live with the lessened performance.

What you DON'T want, or should not tolerate, is what we call "pinging", which sounds exactly like a chain dragging under the engine when you accelerate. This "pinging" is actually pre-ignition, which basically means that because the octane you are using is really too low for the engine, the combustion in the engine is very ragged and un-even, causing the engine internal distress.

While I doubt your cars would experience this "pinging" under hard accleration (it's quite noticeable, this "chain" sound) if you dropped to 89 octane or even 87, still you should listen for it, and if you hear it, don't use that lower octane. I think though that your car's computer will easily adjust for 89 or 87 octane.

I use 87 octane in my V-8 Porsche no problem.

toyotafan6 · April 2005

Here's my take: I think you get what you pay for with just about everything, gas included. I get better gas mileage using 89 octane versus 87, even though the higher grade is not required for my car, a 2001 Corolla.

I used the mid-grade gas (89 octane) in my previous car, a 1986 Honda Civic probably 85% of the time and drove it for 15 yrs with never a ping or knock or any engine problems whatsoever.

I recently increased the tire pressure on my Corolla by about 4 or 5 pounds over the recommended pressure and recently got 34.06 MPG (city) whereas I normally get 30 or 31 MPG -

shipo · April 2005

I think that it is highly unlikely that your car (or any car for that matter) will get better mileage with a grade of fuel that is higher than what the manufacturer calls for in the manual. Why? Simple, if an engine is designed to operate at peak efficiency, said efficiency will degrade to a certain degree as you move away from the recommended fuel grade.

The whole thing is that the different grades of fuel take different lengths of time between the spark event and when the flame front is fully organized. The lower the grade of fuel, the quicker the flame front is developed. Engines are designed with certain combustion chamber configurations and compression ratios so that when fed the proper grade of fuel, the Peak Pressure Point (PPP), which should theoretically happen at about 15 degrees after TDC. If you use a lower grade of fuel than what is called for, your PPP occurs sooner at say 10 degrees after TDC, and that is where "Pinging" or "Detonation" (sorry Shifty, "Pre-Ignition" is where the fuel combusts on its own before the spark event, hence the name "Pre-Ignition", this condition WILL destroy and engine very quickly) occurs. Detonation is in essence the flash combustion (instead of the flame front smoothly burning all of the fuel in the combustion chamber) of some amount of end gas due to the higher pressures associated with the early PPP. The issue here is the degree of detonation, a very little is considered harmless by some and beneficial by others, personally, I'll refrain from comment. Moderate detonation, where you can hear light "Pinging", is where the problems can start. A brief Pinging event when you first press the throttle is most likely harmless, however, if said Pinging continues, engine damage (in the form of burned valves, burned pistons and broken rings) can result. Severe detonation, a condition which is extremely rare in modern engines, can destroy an engine in a matter of moments.

The flip side of using too low of a grade of fuel is using too high of a grade of fuel. Now the flame front takes too long to get fully organized, resulting a late PPP of say 18-20 degrees. Now what happens is that your fuel is far from being fully burned before the exhaust valve opens, and as such, the flame front continues burning fuel right past the valve and into the exhaust manifold. Basically harmless, but since it doesn't convert the resultant heat into mechanical energy, it is also highly inefficient.

Now let us add modern electronics into the equation. My BMW, which carries a "Premium" fuel recommendation from the manufacturer, can run safely on lower grade fuels, however, the computer senses that detonation is occurring and retards the spark event. The delayed spark keeps the PPP at that engines' designed in optimum point. Unfortunately, since the ignition has been retarded (resulting in cooler temperatures in the chamber), the engine is not running at peak thermal efficiency, hence lower mileage and power.

Regarding cars that carry a "Regular" fuel recommendation, it is unlikely that the engine in said cars was really designed for "Premium" fuel, and as such, said engines will not benefit from higher grades of fuel. Using higher grades of fuel in such a car will most likely result in LOWER mileage per gallon of fuel, and possibly INCREASE combustion chamber deposits, which is never a good thing.

Rule of thumb. Use the fuel that your manufacturer recommends.

Best Regards,
Shipo

toyotafan6 · April 2005

well, I am not disputing the facts in your post - I can only speak from my own experience. I check my gas mileage at each fillup. I get better mileage when using 89 octane versus 87...anywhere from 2 to 4 mpg more. Of course this better gas mileage costs more too.

My father-in-law has a Toyota Highlander which the manual states uses 87 octane, but the manual also states to use a higher octane "for better performance".

Mr_Shiftright · April 2005

If the Highlander's manual says you can use 89 for higher performance, that means the engine was designed for 89 but that you can use 87 in a pinch.

There really is no extra "power" in higher octane fuel. It just has a more even flame front, but if your car's engine isn't designed for that octane, it doesn't know it from 87. The car's computer has to be designed to advance timing to take advantage of higher octane. If that's not built into the computer, your engine timing will remain optimum for 87 octane, the design limit.

toyotafan6 · April 2005

well, my father-in-law uses 87 exclusivley (he's very frugal), but I believe the manual stated he can upgrade to 89 - it didn't state that he needed to use 89 necessarily - just that he could for better performance.

as I said, all I know is that the higher octane provides my car with better gas mileage -

Mr_Shiftright · April 2005

It is not uncommon for cars, as their engines age, to require a higher octane due to carbonization, which raises compression ratio; also, any car with a knock sensor might be able to utilize a higher octane fuel. But if the car's computer isn't designed to advance timing right up to the knock point, higher octane fuel would indeed be a waste of money.

djm2 · April 2005

I just purchased a 2003 automatic / 4 cylinder Accord with only 1,592 miles. It was in a garage for two years, and no one used the vehicle. Presently, the car is being serviced and detailed. I know nothing about cars, and I have to depend on my mechanic for all my service needs. The Accord will be my second vehicle, in my stable of vehicles. My other car is a 2002 Ford Mustang, 8 cylinder / 5 speed manual trans.. I will be picking up the Accord on Friday. What grade of fuel should I put into the tank? I had the fuel tank completely cleaned, so I will be starting fresh! I use Premium Fuel in the Mustang, because I tend to "push the gears" late at night, on the open highway, (if you know what I mean)! Life is fun in the fast lane! If you want to enjoy life, you have to push the limits! Best regards. Dwayne

shipo · April 2005

If I'm not mistaken, Honda recommends the Regular grade fuel for your car. That little tidbit of information should be in your owners' manual. Contrary to what many folks think/want to believe, the engineers really do know what they are talking about. If the manual specifies a particular grade of fuel, use it if it is at all possible, it is a waste of money to use anything else.

Best Regards,
Shipo

tanya2 · April 2005

I would use the octane listed in the owner's manual. This would be 87! On the other hand, I would also experiment with different brands of regular gasoline, to see if the engine gives you better mileage. Personally, I like to use Hess gasoline whenever possible, because they pump a lot of fuel, and the possibility of getting contaminated fuel is slim. Once in a while, I might mix a 1/2 tank of premium on a long highway trip, and at the same time, I might put in some fuel injector cleaner. These products can be purchased at the local autoparts stores. Tanya

shipo · April 2005

Why a half of a tank of premium? Unless your car has a computer that can advance the spark timing to take advantage of the higher octane, the Premium fuel will still be burning when the exhaust valve opens, and keep on burning out into the exhaust manifold where your engine has absolutely zero ability to convert that heat into mechanical energy. As such, your mileage should drop when you have that more expensive fuel in the tank.

Best Regards,
Shipo

tanya2 · April 2005

When I put in fuel injector cleaner, I like to use premium fuel to make sure I have enough octane. If the tank contains 1/2 87 octane and you add 1/2 tank 92, you get 89.5 with the added fuel injector cleaner. Plus the premium might have a better additive package. Nothing special. Just something I like to do occasionally.--Best regards, -----------Tanya

concrete1717 · April 2005

BMW, GM, Honda, and Toyota are recommending that fuel be obtained from their list of "Top Tier" gasoline providers. Those fuels apparently contain more than the minimum amount of detergents, set by the EPA, which all gasoline must contain. See http://www.toptiergas.com/index.html

imidazol97 · April 2005

Is this information true? It looks like an email that went around recently.

Mr_Shiftright · April 2005

The "Middle East Oil" chain letter being referred to in post #148 has been going around for years and yes, it contains a huge amount of misinformation. But regardless of that, any call for a boycott is considered a "solicitation for action" and is not allowed in the Edmunds Forums. Hence the related post has been deleted.

thank you

Host

artur_hawkwing · June 2005

Title says it all, I've been using Premium, but now I decided to check and see if that's the best thing to be using. thanks...

shipo · June 2005

Ohhh, that's a difficult one. Why? Well, last time I checked, there were many 1960s vintage British cars that were built without hardened valve seats. So, if your car was so built, and if you haven't had the valve seats replaced (actually, only the exhaust seats are necessary), then no unleaded fuel (premium or otherwise) is going to save your cylinder head unless you retard the ignition timing a few degrees. I'm not familiar enough with the various British cars to know which ones had soft valve seats, and which ones have valve seat retro-fits available (although I presume they all do), so unless you happen to know, I might personally be inclined to visit my friendly neighborhood airport and add a quarter of a tank of 100LL every so often just to be on the safe side.

Having said all of that, if your car was built specifically for Premium, then that is what you must use, regardless of your ignition timing or the condition of your valve seats.

Best Regards,
Shipo

ckhaing · June 2005

The main difference between regular and premium gasoline is that premium has a higher octane number. Octane is simply the measure of a fuel's ability to resist engine "knock" caused by detonation (uncontrolled spontaneous ignition) of the air-fuel mixture in the combustion chamber. Contrary to popular belief, premium fuel does not contain more power than regular fuel. In fact, the actual energy content of high-octane premium is generally a little less than that of regular fuel due to the knock-suppressing additives it contains.

The myth that high-octane fuel contains more power came about because vehicle manufacturers typically require the use of premium fuel in high-horsepower engines. However, it is not the fuel that provides the added power but rather the engine's "state-of-tune, which involves a number of factors including compression ratio and valve timing. When these engine variables are tuned to produce greater power, the possibility of detonation also increases and, thus, the requirement for premium fuel.

ckhaing · June 2005

Actually, in the long run, you are destroying those low-performance honda engines by putting high-octane fuel. It will make them run hotter and more debris in the cylinders because of worng ignition timing.

Original message by -badgerfan [gregoryc1] as follow.

"I guess your preference is to waste money"! ----That is a "judgement call" on your part!----- In the Honda manual it states that the owner can use 86 or higher octane fuel in the engine.----- Not all fuels sold at stations are the same. I don't drink, smoke or gamble, so my only problem is burning premium fuel. That is not bad when you consider the results to the other things. (Drinking = health / liver issues, Smoking = Lung Cancer amd Gambling = loss of savings and life style). I will take purchasing Premium Fuel as a personal issue any day! In addition to purchasing that high priced premium fuel, I also change the oil and filter every 3,000 miles, because I love a clean crankcase, and clean oil in the engine. The oil is so clean on the dip stick of our two Honda engines, that I can harding see the old level, and the 2003 Accord has 20,000 miles on the clock. Yes, I do spend money on "preventive maintenance", and I love the total experience. Just yesterday, I took my wife's 2004 Honda Civic for a 3,000 mile oil and filter change at the dealer. I had a great experience. I arrived at the dealership with three cups of flavored coffee,(one for my wife, myself and the service writer), and in addition, I gave the mechanic $5.00 as a tip for the service rendered. Yes, I love to spend money on my things and on people that I like. Life is just too short to be cheap! -----And, I never knew anyone that was able to take their money with them when they died.----- Don't try to bring the war in under budget! ---- Life is more than a "balance sheet"!

Mr_Shiftright · June 2005

High octane fuel has no more power in it than a 34" baseball bat vs. a 32" baseball bat. It's what the engine "does with it" that counts.

The myth also was created by older cars, wherein you could in fact add high test fuel and then manually bump up the timing (advance it) and generally notice an increase in power.

Now of course all this timing business is done by computer, which has a map that optimizes performance and octane for your particular kind of engine. If you aren't mapped for high octane fuel (that is, if the computer won't advance the timing enough for your engine to take advantage of it), then it is a complete waste of money. Even if it is mapped for it, you may gain just a minimal amount of power at the expense of fuel mileage.

High octane just has a smoother "flame front"--it burns more evenly, so combustion is optmized in that sense.

But there's no more power in it, no more energy I mean per volume.

What about fuel types & gas mileage?

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