re: “Name brand” gasoline

Well, it can be complicated. I'm going to give you some gross oversimplifications:

First off, Techron is the real deal, and I have seen the test articles and raw data on it at an independent lab. It actually does something useful. Chevron is not the only brand that has it, but you can also catch BOGO sales of it in bottles at parts stores. There are maybe 1-2 other additives with the same active ingredient, but I forget who makes them.

Second, of all the "discount" gas, Kirkland is actually considered a "Top Tier" fuel by the industry. IDK about Sam's Club fuel. Costco actually makes a big deal out of their fuel having a high end additive package.

Third, if the gas comes down a pipeline, there are times when it is separated by water "slugs" from something else coming down the pipeline. SOME cheap gas brands are extracted from the last part of the gas just ahead of the slug, and have a bit of cross contamination.

That's all the OT needs for maximum Baw Dozer motoring. It only gets more technical and boring from here.