David, don't want to burst any bubbles either, but comparing performance of an engine on 87 gas and old head (with a possibly defective valve) with that of an engine with a brand-new head and valve train on 93 gas is not exactly apples to apples. You need to compare the performance of the car by changing only one variable at a time, otherwise your comment is pointless. I can not possibly think oh how low octane gas could have caused valve damage. I've been burning 87 gas since 1990 only occasionally switching to a few consecutive tanks of high test (read: high price) stuff only to find out once again that the biggest difference was in my wallet. Never had any engine trouble. In fact I sold an '87 Acura Integra with 135K mi on it that burned no oil, got over 30 MPG and hardly registered any numbers on the smog test. Though its body left something to be desired, that engine performed flawlessly after all these miles of regular gas.

No bubbles burst.