I've been using them as long as forty years (back when it was MICROLUBE). While the fuel additive is newer, LC-20 seems to keep problems away. I haven't bought any recently, but need it. It also makes the best penetrant I've found (thank you, Molakule, for that recipe).
Took my FIL's old Winchester (mid-1950's) for which I had no plans. Quite a bit of surface rust from sitting around in a closet; cosmetic. Don't know anything about the maintenance (but lightly used, tight action). Cleaned it in an ordinary manner and finished with a wipe-down with LC-20/#204S. Forgot about it. Opened the soft case after about two years and was surprised to find all rust gone. Bluing glowed. You should understand that I didn't care when doing the work. I just did with it what I would have done with a number of tools, and this recipe always works well. (Add some acetone for the nasty rusted fasteners).
Handy stuff. I believe they do what they say they will. On some of the 6-7 vehicles with an accumulated 300k miles I've used them on (to forty years of age), mpg improved. On others, no difference. My 1973 Jacobsen lawn mower was still running well (after a lot of pulls) when I gave it away in 1999. Plenty of those little cans of Microlube went through there to offset the hours of huge yards cut as a teenager, and then for years wtih several other family members before I got it back.
Had to re-tune one of the cars as the idle was too high once I was using FP-60 in it. Oil consumption didn't change, and on the oldest it decreased under hot, hard highway use. Oil analysis on another showed better numbers using it (after ARX) and a lifetime of synthetic. I used REDLINE on that car, and wanted a no-compromise 8-10k OCI. (Intervals were very short time-wise).
Odis Beaver is always a pleasure to deal with, and the guys who now own LCD have always been the same. I've had consistent performance.
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