I go thru plenty of bottles of single malt between fill-ups. But to answer the initial question, Sunoco, BP and Shell in that order. I won't go to an older filling station. Here in New Jersey we are not allowed to fill the tank... Note: I prefer to have an attendant fill the tank.

 

I was following another forum where in CA this individual mixes 1.5 gal of racing fuel to every 12.5 gals of 91 octane gasoline and says it improves performance and of course raises octane to about 93-94. Another one claims to add 2 gals of E 85 with every fill of 91 octane to increase the octanes. I live in the Colorado Front Range so 91 is as high as I can get. In lower altitudes I can get 93.
Anyone try mixing E 85 with 91?

BTW I have found that Shell 91 octane premium is best for my baby. That said I only had one poor experience with an off brand premium. Even Safeway premium is fine

I like the idea of a single malt every 1000 miles, I'm going to try that