I like the 3 in 1 oil. I use it for just about any-thing and haven't seen anything that has been around for as long, or new, that works any better. I have seen WD-40 actually make metal rust quicker and can't tell you why but have seen the proof. Other than 3 in 1 the other favorite I have is Marvel Mystery oil. Like I said before, I usually don't use any-thing in my R/C engines for after run but those two are what I use for cleaning and breaking engines free that have been sitting for a while.