It makes you go faster by lightening your wallet more.

There's a general misunderstanding about octane. It doesn't contain special power boosting ingredients. It exists to keep high performance, high compression engines from damaging themselves. They need higher octane gas in order to prevent pre-detonation. Compressing a substance creates heat. The high compression in some engines can cause enough heat to make the gasoline ignite before the spark fires, which is not good. Octane helps prevent pre-detonation by making the gasoline burn slower. Putting high octane fuel in an engine that doesn't need it accomplishes nothing but making oil companies richer. The exception, though, is on modern fuel injected, digitally controlled engines with knock sensors that can advance and retard the ignition to the threshold of pre-detonation, yielding a wee bit more power.

Motobuddha does not tergiversate.

As he maintains, more octane does not mean more power.  Unless you have a detonation (pinging problem) on regular grade gas, it usually means less power.

The best idea is to use what the manual says to use.  Using a higher octane pleases only the oil companies.

One comment on Moto's statement, "The exception, though, is on modern fuel injected, digitally controlled engines with knock sensors that can advance and retard the ignition to the threshold of pre-detonation, yielding a wee bit more power."  This is only true if the car were designed for the higher octane fuel.  
 -- IOW, my wife's SUV will not make any more power because the knock sensors sense a better capability for suppression of detonation.  It doesn't detonate on 87, so it won't advance the spark if she puts 100 octane in it.  
 -- His point applies to cars that are supposed to use premium, like mine.  If I put 87 in it, the sensors and computers will readjust timing and mixtures, etc., to do the best it can with that fuel.  A couple of times I have had to put in some 87 octane -- it noticeably decreases power, and, while I only have one data point, it decreases mileage.

BillF6531 wrote on 08/17/11 at 12:42:56:


Since hers was made in 1998, I doubt it is that smart.