At least in the past, the only gas that a station sold, that met the franchise name specs was the premium grade. EVERYTHING ELSE, was open market government minimum spec unleaded gas. I use to buy diesel fuel buy the tanker load, and it all came from the same refinery.
If your engine doesn't run as well as you think it should, try another brand, you may be pleasantly surprised. TRY to AVOID ETHANOL, but that is getting tougher everyday. I think I read for each 10% ethanol, reduces the lubricating quality of the oil by 25%.
Once the 2 cycle oil has been mixed with the gas try to get it use in less than a month. Mixed gas seems to loose it punch quickly. If you need to readjust your carb setting, on older gas, try new gas first you will see a difference.
The gallon in the truck first trick is a great idea, except I drive a diesel. HA.