I can't say that Sam's is worse. However the major's have strict testing for gasoilne and they reject anything that does not meet the spec. That gas is then sold through several "minor" branded stations (I won't mention their names). Yes it does come from the same refineries and if you are buying 87 octane you are getting 87 octane. However it is not necessarily the "same" gas as at the brand stations. Sort of like generic and name brand. Sometimes it's just a matter of saving money for the same blend, but sometimes its not. I don't use the off-brand stations but that don't mean I make the right decision. I'm not real sure with this particular engine that I would worry about the gasoline specs too much.

Don't waste money on anything other than the octanne recommended.

I will find this post amusing as the other posts on synthetic oils and Slick 50 and other products tend to have some very staunch supporters of spending more "just to be sure". I will take interest in seeing what gasoline people use.

My worse experience had nothing to do with the gas, rather I got dirt in my tank from one of the store / gas combinations and I am real picky as to how the station is maintained around the gas tank filling area. Minor nit, but I only want burnt once on any one thing.