Gas ? Octane ?

badcertified · September 11, 2003

Hi You All , I'been reading some thoughts on Gas and Octane . I was always under the assumption the higher the Octane the fuel would burn Hotter , therefore Cleaner , . What I have been reading on this post say's i'm wrong ! What is the general idea for best brand and best Octane for 5.7 in a 98 silverado. Thank you in advance ! P.S. I love reading these posts , you guy's know a lot about GM Trucks .

MCourson · September 11, 2003

Im not certain what octane is best for you but I do know that lower HP and lower compression engines can run better on lower octanes. In kart racing back when we used to run gas before we starting burning methanol we would always use 87 octane. In racing conditions, on a stopwatch 87 was faster than the times we ran using 89, 93, or even VP red which is 105 octane.

bigtruck21 · September 12, 2003

the best octaine will be the lowest that doesn't cause pinging. Try different brands and different stations also. Some brands have different additives and some stations might have older tanks that have more water or setiment. Keep track of mileage on a "pure" tank and go with the best one.

AlanTDickey · September 12, 2003

Higher octane gas is used as a knock suppressant -- to lower the volatility of the fuel. This is a necessary evil in high-compression engines to prevent a more-explosive fuel from firing too early, which causes knocking. Thus, as bigtruck21 said, you want to use the lowest octane rating (most explosive fuel) that does not cause knocking.

The perception that high octane means more power is wrong.

Just because really bada$$ engines must use high octane does not mean that a lower-compression engine will have more power using the same.

badcertified · September 12, 2003

Thank you guys for your help ! I went to some gas barnd sites and they are confusing also ? but I am going to shift down to 87 on my next fillup and see where that takes me . thanks again , this is a great site !!