Fuel from one company is pretty much the same as anyone else's. Arco, Chevron, Costco, Unocal or Walmart fuels probably come from the same place. My friend works in the lab at the Chevron distribution center and they sell to everyone. The additive package may be a little different but the base stock is the same. I have heard that Costco has more injector cleaner added, but that is there deal. Is it more than Chevrons, I do not know. I've never asked.

I used to know the state regulators in Oregon. They checked octane ratings and they never were off more than one half of an octane. 87 octane was never more than 87.5 and never under 87. The refiners were that good. The samples even came from stations that did not pump much fuel.

Think about it, I dislike Walmart as much as anyone, but they know what would happen if the fuel they sell ever came up short. Often there fuel is the best available. There oils are tested often and they are a very high quality. There synthetic oil is about the best available. No one would believe the test results.

It may be true that fuel additives are a waste of money. I've never heard of any that really work. That is double true for diesels. However, I still add ATF to some of my diesel fuel. I have a mechanical fuel pump and the lubrication may just help. People that know kind of laugh at me.