Bear in mind, you'll likely lose a little mileage due to running winter gas. Not every engine seems to show a difference, but some do. Also, if your engine was running hotter before it was burning gas more efficiently. I suggest running a 195* thermostat. You may also try running a test. Run 5 tanks of cheap gas and take down your mileage, then run 5 tanks of quality gas (chevron, etc.) and see if there's a difference. My 91 2wd got slightly better mileage when I switched over to quality gas, though it took atleast a couple tanks to really start to notice the difference. And no, I didn't drive any different, I never really do.
