Originally Posted by Majdnoon
This. I also fill up almost exclusively on Costco/Sam's Club gas so I wanna know, is it doing harm or good for the engine? Anyone wanna help us out with that?
Personally, I'm in the camp that gas is gas leaving the refinery, with the difference in the additives. Reading I've done indicates Shell and Chevron additives are effective.
I do try to use busy stations (fresh gas) with high flow (clean filters).
Costco refomulated their gas to use 5x the detergent additives vs. before in their Kirkland Signature, so I'm fine with that.
YMMV, of course.