I think what the author is trying to convey is that even after the mixture is lit, additional compression effect (from combustion) on the portion of the mixture not yet burned causes a delayed/extended burn relative to a lower octane content because - if the octane rating was lower, the developing combustion pressure would ignite the balance of the mixture faster.

Maybe he is saying it in a round about manner, but in any event, my eyes sure can't see it and I sure can't prove it one way or the other. <img src="/forums/images/graemlins/lol.gif" alt="" /> I'll leave that explanation to others. All I want to know is what works the best.

I do think the article makes a good suggestion to try a few brands to see if there's a noticeable change - something I'm guilty of never doing..... I usually go to the nearest Exxon station because (at least here) they went through a time of building a lot of new stations that were located on nearly every interchange and they had clean bathrooms. IIRC, my wife participated in the decision about which gas stations were the best. <img src="/forums/images/graemlins/wink.gif" alt="" />

Frank