Originally posted by Big Jim:

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Actually, I'm mildly disappoited that my car was factory tuned so that premium fuel is not that critical. I'm also disappointed that there has been so little equipment wise to enable me to tinker with the settings that I used to be able to do by hand.
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It must not get that hot in your part of CA because mid summer temperatures in Phoenix make it evident that 91 octane is NOT enough. Knock or ping... I don't know, but the car definetely looses power after making a predet type sound. 100 octane resolves this issue, but is expensive... auto parts octane booster sometimes helps, unless I'm doing lots of city street driving.

So how about this... if you live where it can reach 120 degrees, drive with the a/c on, rarely let the secondaries close, and don't have enough faith in the knock sensor to risk your engine, then you CANNOT run less than 91 octane.

morbid 2000 Contour SVT (black)