I have a State Oil location not far from me that, I think, carries 90 octane non-ethanol. About the only non-ethanol gas left in the area. It's quite a jump from the $2.09 regular at Exxon et al. Still, I might try it in the Buick's 3.6, not so much for extra power (I don't think the 3.6 V-6 has all that high a compression) but to see if the mileage improves on a highway trip.
The manual doesn't recommend premium for this car. Once I put premium in the Park Avenue with the 3.8 engine. The gas mileage went down, and came back up when I switched back to regular. So I doubt I'll try 93 in this car.
