So, we like additives to extend our engine life, keep them running at top performance, and maybe even get some extra mileage with our fuel. the question is do we use additives and ignore an upper cylinder? Is a ucl as effective as an additive? And is there any evidence or proof that an upper cylinder lubricant is effective at lessening wear and keeping your engine in top shape? For what it's worth I'm using ceretec/Mos2 with good oil. As well, I've been using Lucas ucl for the last year. I want to get at least a half a million kms out of the Prius. So far so good.... Thanks in advance...