we settled on the "winter blend" fuel from this particular distributor.. which happens to be American Gas & Oil. I have no idea where they purchase from, and neither does anyone that works in the local station...
needless to say, the only thing I could do about that, was to start buying fuel somewhere else.
The only other retailer on this side of town other than Speedway (I don't trust their pumps, they haven't been certified since about 2000; and half a tank is 17 gallons there, 14 gallons across the street), is BP way the hell up in Cooper. So I started buying it from BP again. I say again, because last summer, they were "local" outlet for a bio- refiner that opened about 20 miles west of here... well, they lasted about ten months, long enough for the price of soybeans to about triple, then they went tits up... they only brew for the co-op customers now.
Then I had a dumbass attack and remembered I haven't changed my diff fluids, so I changed them, & the transfer case... well, since then, I haven't had a chance to fill it more than once, but it seems like there's less drag in the driveline...