I actually think the Zmax was on TV being hocked by one of those loudmouth pitch-men at some point. Comes in these beaker-shaped bottles, and I think I have seen it at wally world.
I've never seen X-1R in person, even on the internet only a few people seem to retail it. Keep hearing all these good things about it, though I'm still leery about adding magic potions to engine oil, especially with a wet clutch. Anyone who's tried it have issues with this?
The idea behind these engine treatment additives is to create a super-slick motor oil, by adding stuff like paraffins (wax) and teflon in various forms. Some increase the viscosity of the motor oil, which serves to help cover up worn rings or valve seats. Some have agents designed to be absorbed by and swell up seals for the same purpose. From what I've heard, almost all of them are just masking symptoms rather than actually solving them.
There's this new stuff I've seen advertised in popular mechanics called Xado "engine revitalizer". Claims to use nanotechnology to somehow fill in scuffs and wear to moving parts. It's very expensive, like $50 for a small tube, and even they claim it can take hundreds of miles for effects to be noticed. Sounds like they're mitigating disappointment right out of the gate.