There’s no way to talk die hard additive fans out of using additives, so I won’t attempt to do that. But for anyone who is “on the fence”, actual engine testing data says you don’t need them. Assuming that you use top tier gas regularly, you will be a teeny tiny, little bit WORSE off using extra Techron (or any other additive) than just using the top tier by itself. Our testing over many years (I’m retired from a major oil company) clearly and repeatedly showed that it was entirely possible to use too much detergent. That’s because the detergent itself leaves a tiny bit of residue. So if the engine is clean (which it will be with top tier), then extra detergent won’t make it any cleaner, but it will make it a teeny tiny bit dirtier by the amount of detergent residue left behind. It would be sort of like using an ultra heavy load of detergent in your washing machine. If you did that regularly, it wouldn’t rinse out very well, and eventually, you’d have a collection of soap scum in your clothes. In the case of gas additives, the point of the above message is not to say you will hurt your engine by using them. The teeny bit of residue left by extra additives isn’t enough to hurt anything. The point is, if added on top of gas that already has top tier additives, it isn’t going to help either, so you are wasting money.

There are only two situations where you might gain some benefit from extra additives. One is if you have a seriously dirty engine from tens of thousands of miles on cheapo gas. Even there, the benefit isn’t huge. Just plain old top tier will do as much in a few dozen tankfulls as extra additives would in a tank or two. Neither approach will get the engine back to clean as new, but either approach will get it well over half way back. That one I know from looking at actual test data. I cannot vouch for this next situation from any testing I have personally seen, but several on the forum have reported that Techron sometimes corrects gas gauge problems in earlier generations of Vettes. I have no idea what percentage of the time it works, but fuel sender replacement is several hundred bucks, so if you gas gauge fails in an earlier generation Vette, why not try it. Even if it only works 1 time in 100 (and forum scuttlebutt says it works more often than that) for a few bucks to have a chance of saving several hundred bucks, odds say you should try it. As far as I know, there is no comparative data even on the forum about whether using extra Techron every now and then would reduce odds of having a gauge problem in the first place. Somebody might say “I’ve used top tier plus extra cans of Techron and never had a gas gauge problem”, but tons of people haven’t used extra added Techron and never had a gas gauge problem. So to know if it was effective as a preventive measure, you’d have to do a controlled, statistical study, and to my knowledge, nobody has.