At your own risk!!! For the brave and the risk-tolerant only, put five grams per liter of Hexagonal Boron Nitride, also called HBN:
https://www.bulletcoatings.com/product/hex-boron-nitride-hbn-powder/
in your engine oil. Smooth power, like wow :-) The stuff is actually very non-toxic, it is the primary ingredient in many women’s cosmetics. An extremely fine powder, and extremely slippery. Do NOT put it in any transmission…