ORIGINAL: DavidAgar
WD 40 is not recomended for the engines. Another choice is Marvel Mystery oil, available at any auto parts store. As mentioned, a few drops in the carb, prop her over a couple of times and you are done. As for needing to do this, the debate is on. I have been doing it since I got into RC 30 plus years ago and I have never had any problems with rust or engine's being siezed, so I think it is very important and I do it to every engine upon completion of a flying session. Good Luck, Dave
I agree about the WD40, but a lot of folks still use it. I suggest you also consider using a good AIR TOOL oil, like Marvel AIR TOOL oil., It is very inexpensive compared to "after-run" oils, and its main job is to lubricate and prevent rust in air tools. You can buy those in small bottles almost anywhere and I just bought a case last time, got a LOT of engines. There is no need to pay ridiculous prices for after-run oil in my experience. Better to use it and not need it than to need it and not use it! Otherwise, there is always Boca Bearings.
For what it is worth. Terry Joe