I have yet to see any harm that Red and Tacky (R&T) has caused to any locomotive applied. I used R&T on my Weaver VO1000 when the O.E.M. grease jammed the gearing from the get go!
I never have an issue when running it lately. I think the o.p. is reading too much into it. The proof is in the pudding. Show me a damaged loco from applications of R&T. Until then, I am using it. It's cheap, readily available, affordable and as others said the grease clings to the gears instead of dripping off when some heat is present.