High octane gas helps your engine

Posted: Fri Oct 13, 2006 7:35 pm

Some people saw this on TV. Some heard this from those who seen it on TV. Some heard from those who heard from those who seen it on TV. Premium high-octane gasolines are said to "drive your engine clean," reduce auto maintenance costs, and benefit cars in other ways.

Induced by these claims, millions of motorists have paid the high prices for “supreme,” "ultra," "super," "gold," and other premium gasolines with octane levels as high as 94, thinking that the benefit of these gasolines justified the high price.

As a combustion researcher I can say that there is no benefit in using higher than manufacturer recommended grade gas in your engine whatsoever. It does not hurt technically, either, but it hurts financially a lot. If your manufacturer recommends regular gas, and by any chance you feel your car is running better on premium gas that means you have engine problems to take care of.

If someone needs official confirmation from US government, here it is:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
http://www.ftc.gov/opa/1997/06/exxon.htm
http://www.ftc.gov/opa/1996/09/exxon1.htm

Driver Joined: Sep 25, 2006 Posts: 107

what about cars that say they require higher octane gas?

Posted: Tue Oct 17, 2006 8:14 pm

Misha wrote:

there is no benefit in using higher than manufacturer recommended grade gas in your engine whatsoever.

Sure I'm not telling you to use regular, if your owners manual tells to use "ultra" or smth like this. All I'm saying is that using higher grade than manual says, does not give you any benefit Smile

Driver Joined: Sep 25, 2006 Posts: 107

sorry.. poorly worded question..

if some engines require higher octane, lower octane must be bad for them. If lower octane is bad for some engines, why isn't it bad for others?

Posted: Wed Oct 18, 2006 9:47 pm

just to make sure I understand the question properly. Are you asking about what octane rating is and what is it for?

Member Joined: Nov 15, 2006 Posts: 18

Compression and timing are what causes you to have to run premium. It takes more heat to ignite premium, so it won't detonate, or light up before the spark plug fires.
Higher timing will generally give you more power at the higher rpm range, taking away from the lower. Now if you have a car such as an Integra GS-R with it's relatively high compression engine, and you put 87 in it, it will detonate. Then the knock sensor will have signal the ecu to retard the timing, causing you to lose power and put a pottential danger to your engine (detonation= super bad).
So don't put 87 in your sports car, thinking that there is no difference, engines are designer for specific octane rating so, as said before, put whatever is recomended by the manufacturer.