Far from an expert, and Jack will correct me if I'm wrong, but the key to what fuel you should be using is if you hear the engine pinging. The real risk to running a high compression engine with insufficient fuel is to get pre-detonation, which will eventually burn through the pistons. If you don't hear pinging, then you are probably ok.
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Charlie McCall
1985 DeTomaso Pantera GT5-S #9375
"Raising Pantera Awareness across Europe"
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