Agree with Jack.
I have never seen an additive withstand any credible independent testing.
What they do have going for them is unbelievable profit margins.
One more thing to consider. How many cars are actually sent to the junkyard because their well-maintained motor simply wore out?
I have not yet owned or seen a motor that died in this manner.
What typically kills a motor?
3)Oil not changed
4)Timing belt snapped
5)Head gasket failed
Low "Slipperyness" of oil does not make the list.
Of course, I live in the northeast, where electrolytic reactions always cause cars to 'meet their maker' long before the motors die...
1986 300E 5-Speed 240k mi.