[jimberg]

The cost difference betwen 87 and 92 ranges from 14 to 22 cents here in Minnesota. The interesting thing is that that spread always seems to be there. Even when gas was 1.20 a gallon for 87, premium was 1.34 to 1.42. Taking the worse case, you would be spending 18% more to get premium. Gas just hit 3.20 a gallon for 87 yesterday. Premium is now 3.42. Now it's only 7% more to get premium. It's a better deal. If you emptied your tank once a week for an entire year, that's only an extra $176 for the year or about $15 a month. Do you really want to de-tune your fun for $15 extra a month?

We can also purchase non-oxygenated premium here in Minnesota. That means it's pure gasoline. I get at least 10% better gas mileage when I use it than when I use the oxygenated crap. It's actually cheaper for me to use than if I detuned my car to use 87.

Vamp89, Why is your timing set so high? Have you put your car on a dyno to confirm that you get the most average HP at that much advance?