Gas In Grand Prix Gtp's

[gob 455]

I ran the car to empty, put in $20.00 of 87 octane in. About 5.5 gallons. Under light acceleration, I had 0.0 to 0.2 degrees of knock retard. Driving, I had none even with a minor amount of hilly road. From 65 mph to 95 mph I had up to 5.2 degrees of knock retard. So what dose this mean. It knocks under hard acceleration. So I stand corrected. I gusse I'll put plates and insurance on my 86 Sunbird wagon. It gets 30+ mpg on 85 octane, with out any screwing around. As for the last part, I always tell people to read their owners manual. The original poster probably knew it specified premium fuel, but he still asked the question. What are the long term affects, and how long can you get a way with midgrade? Their are too many variables to know.