Since the weather is starting to get crappy, I know that i'm not going to be running my R/C car anymore this year. Is there anything I should do to the engine? Someone told me to take off the backing plate and coat the crank and connecting rod with after run oil. Should I do that or just put a few drops on top of the piston and give it a few cranks?

The very best method is one I heard from an R/C expert. He said to fill the tank up with fuel and keep driving it all winter!

I would take the backplate off. Flush the motor out with wd-40 and then coat the conrod bushings with a few drops of oil. Piston and sleeve with some oil and also the connecting rod. After that it will be fine.

put a liberal amount of after run down the glow plug turn it over on the box for like 10 seconds or so put some oil down the carb and hit it on the box again etc then take it off and put it in a zip lock bag make sure to get all the air out also

Yeah what Mike said. Actually, that is what I do if I ever forsee my trucks sitting for a while.