...why would someone consistently using Chevron gas need to put this stuff in the tank? I consistently fill up at Costco. Since all stations have been upgraded to their high performance additive, I haven't bothered using any additives in a bottle. I still have some though. Not sure what to do with them other than maybe add them on the road or once in a while just to get rid of the stuff.
From another contemporary thread
A common misconception with Top Tier fuel is that it's all you need to counter the additional gumming from ethanol fuel, those additives simply aren't enough...<snip>
I'm not sure how you would test for 'too much' or 'not enough'. If you used Top Tier gasoline even occasionally, that should keep the crud level manageable, or under control. Is there any benefit to keeping the fuel system even cleaner, beyond what the included additives accomplish?