Guys, even simply switching from one octane to another can mess with the PCM. It takes time to adapt to changes, which is probably MOST of your problem.

Pick an octane, and stick to it.

My brother in laws Series II regal gets about 200 miles to a tank. It eats more than my father in laws 1997 360 ram

That damn Regal is way past due for a tune up

Try to change the Tstat back to 195 for the winter and see what does for your milage. The car runs richer when its colder. But ever since I put my 180tstat in, I' noticed much poorer gas milage. Im changing it back to 195 tommorrow, fillin my tank and seeing waht happens. It'd be cool if you did that to so we can compare each other results.

In that case I am going to go back to 93 and stick with that. That was when the gas guzling started, when I went from 93 back to 89. This past fill up.

I think i have to stick with my 89 for now. It'* same price as 87 here in mankato and i can bite the bullet when i NEED to fill up at the 'rents place. Premium didn't seem to do too much, but i might try again.

I dont even have my old 195. I lost it somewhere.

I'm noticing my gas mileage going down too. I got around 290-300 miles to the tank last week. I filled up two days ago I think, I've driven about 50 miles and the gas gauge is VERY low for driving 50 miles while driving normally. I'm going to watch it and see what I have at half a tank. I hope my gas gauge is just screwy and not my mileage.

What brand of sensor did you buy? What operating temperature is the car running at?

Yeah, if you got a Bosch that will explain a lot.