thats more then likely in your head that you got better fuel mileage…
and its recomended that as your engine gets older, you should put a higher octane in…
and the car gets older and more carbon builds up its does not desipate heat as well, causing dedonation…
if you can do it often, throttle body spray can reduce this build up…
i use it every 2 weeks, and some times i use a bottle of DISTILLED water and lightly spray water into the throttle body and that is the best type of combustion chamber cleaner you can get… its like a steam cleaning for your pistions and valves[/quote]
Accually I crunch the numbers to see what kind of fuel mileage I get from the various types of fuel. The car was my parents before I got it and my dad tested to see what types of mileage he got on 87, 89 and 91 octane to see which provided the best mileage. And no, not one tank these were month long tests. I accually still have a spreadsheet with all fill ups from the day they bought the car back in 1993 till this year.