Is Higher Octane better
watso
Member Posts: 2
Is higher octane better for engines?
I have a 97 Volkswagen Jetty GAS and a 97 Volvo 850 GET.
Due to the increasing gas prices my wife wants to switch from 92 to 89 or even better 87.
I am worried about what this might do to the engines over a long period of time.
Is there any evidence on why higher octane is better for your car? Any advice on this matter will help. Thanks
I have a 97 Volkswagen Jetty GAS and a 97 Volvo 850 GET.
Due to the increasing gas prices my wife wants to switch from 92 to 89 or even better 87.
I am worried about what this might do to the engines over a long period of time.
Is there any evidence on why higher octane is better for your car? Any advice on this matter will help. Thanks
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Comments
In short, check your manual. In order to get higher performance from the same size motors (and not drastically increase consumption or emissions), manufacturers are switching to ignition and fuel systems that require higher octane. This should be taken into consideration when puchasing a vehicle.
Use of 87 or 89 octane gasoline in a car designed for 91+ is usually OK for a tankful or two but performance will probably seem sluggish and continued use may result in engine damage.
If you calculate the costs of octane per dollar (or penny) you'll see that 89 octane is usually a bad deal. I'd alternate between tankfuls of 87 and 92+ if I wanted just a slightly higher octane in my car.
--- Bror Jace
Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump. The misnomer about octane is that the higher the rating, the better or more smoothly your car will run. In fact, premium gas can be bad for your engine if it was not designed to run at a high-octane level.
Although it may seem that the term preminum or high octane implies that more energy is available, premium gas does not produce more energy than regular or mid-grade fuel. The octane grades are designed to accommodate engines with different compression ratios. High compression engines, found in most performance cars, require a fuel that burns efficiently at a higher temperature. That';s what premium fuel does, it burns hot under high compression. In a normal engine, premium fuel does not burn completely, resulting in excess carbon build-up and carbon fouling of the spark plugs. The end result is a less efficient engine that requires tune-ups more frequently. Oh, yeah, did I mention it also wastes money?
The only time you might need to switch to a higher octane fuel is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars. Check your owner's manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.
For example, a 1999 Toyota Camry V6 should run on premium fuel. A nice car maybe, but not exactly a luxury or sports car. It's also even more of a suprise since other manufacturers extract similar (or sometimes more) power out of regular fuel with an equal displacement. I'm not sure about later models, since Edmunds seems to have gotten rid of that info on thier current new car pages (bad Edmunds!) and I haven't bothered digging around elsewhere.
So check your owners manual or look on the car, as it'll usually have a sticker indicating the fuel requirement. (and check before you buy). "Regular" cars may need "premium" fuel as well.
btw-
you can get to old pages from '98 or '99 by going to
http://www.edmunds.com/newcars/1998 or
http://www.edmunds.com/newcars/1999
For trucks substitute "newtrucks" for "newcars".
couldn't agree with you more.
My Z3 says to use gas with an octane rating from 87-91. I've never heard the car knock with the cheap stuff '87, but some say my engine automatically retards combustion to compensate for the lower octane rating.
I may be driving a retarded car, but I can't tell the difference.
On the additive thing - I can't find a gas station in my neck of the woods that doesn't advertise some form
of additive e.g. Chevron has techroline, Shell has their own and ARCO says there's no better gas with their
additive.
... BUT, you will inevitably get a bad tank of fuel now and then. That's why I use a bottle or two of a good fuel injector cleaner each year ... along with some Isopropyl gas dryer to keep the moisture out of my car's system.
Steverisity, I'm not sure if your M3 is retarded or not. You could drive the car hard (some flat-out acceleration) using your current fuel, then switch to something like 92-93 octane for a tankfull or two, repeat the 'test' abd see if you notice any change. But, if you bought the car just for its styling (or to attract women), 87 is probably fine. >;^)
--- Bror Jace
I used to throw Techron in every once in a while. Haven't used it in awhile. As far as brand A being better than brand B, I don't notice a differnce. Maybe there are differences? But how can you compare?
I've seen the immediate results of Redline SI-1 in my buddy's VW Rabbit (a drastic increase in mileage) and I saw the instant effect of adding Isopropyl alcohol to a V-8 Ford truck that got a bad (watery) tank of gas. It went from sputtering and almost stalling out ... to running perfectly fine a minute or two later.
Basically, I think people should use 1-2 bottles of SOMETHING every year. Oh, and you should add them a tankfull or two before an oil change as the cleaners can make their way into your crankcase and dilute your motor oil. I know that Chevron warns specifically about this.
Just avoid any cleaner/additive that admits to containing the corrosive alcohol "methanol." As far as I'm concerned, this junk should be illegal to sell as a fuel additive.
--- Bror Jace
Good point on adding the additive right before a oil change.
You should use the grade recommended in the manual.
nrauch, it's common for ignition systems to start acting up as they age. My Dad's Mercury specified 87 octane but as it aged, he required higher octane to keep it from pinging while under load (accelerating, hills, etc ...). I had a buddy with a 4.0L Cherokee that did the same thing.
You can simply use the better (more expensive) fuel or you can try to find out if it's something in the timing, ignition, etc ... but that can be a nightmare to diagnose. Your choice.
--- Bror Jace
If you are satisfied with the performance of your car on 87 gas, I'd stick with it and save the money.
Still, if it were me, I'd at least OCCASIONALLY use a few tankfuls in a row of 91+ octane and 'exercise' the motor once in a while.
--- Bror Jace
One of these days I will take your advice and try the 91 octane just to see how the car feels. Right now, I feel fine using the 87. thanks!