Contour Enthusiasts Group Archives Forums General General Premium Fuel Question

I need some more advice on the 96 Mystique, 5 sp./V6 I just purchased. The vehicle has 42,000 miles on it and is in excellent condition. It has been given tender loving care throughout. The previous owner informed me that the car has only had premium fuel. I told him my SVT needed premium but didn't see why he would run the 170hp duratec on premium. He indicated premium goes through more refining which removes impurities and as a result his fuel filters are always very clean. The question of the day is whether I should continue to use premium in the Mystique or whether I should fill the tank with regular. What's everyone think?

It depends on the car.

My SE Sport ran its best on 89 until I installed the Diablo Sport chip.
With anything higher, it drank it like water...

See what your MPG is on high octane and switch to 89 and compare after two or three tankfulls.

All grades of gasoline contain the same detergents.
The only difference is the cumbustion additives that control the duration of the burn.
The lower the octane the faster the burn.
Higher Octane is actually better for Summer, and Lower Octane is better for Winter.

The best gas to use for your car is what the owners manual suggests. In this case regular unleaded is fine. The only change from this if because of mods you get pinging then move up a grade until the ping stops.

In actual fact regular gas has more btu's (or heat) in it that premium. This is because the premium is formulated to vaporize at a higher temperature and compression without preignition burn that is the ping. All grades of gas are formulated for the the season of the year they will be used. Summer regular will vaporize at a higher temp then winter regular. The same with the other grades. So you can stay with the same grade summer or winter.