It comes with miraculous claims. No one seems to really know, but I read here somewhere by someone in the oil industry saying they investigated it, and it did not work well in an engine. In a gearbox, that might be something different. I tried using some once, and I am sure it gummed up the oil filter. Probably it is o.k. if you have a cheap paper filter, but with a PureOne filter, the pores are so tiny that I am sure they got gummed up. I still have the filter, but I haven't opened it up to inspect for the MoS2 paste. That is why I don't use it in an engine anymore.