I use to be into gas powered cars and I polish my engines to keep it in top condition. For the experior I just use a brush and spirit. As for the inside I will take the whole engine apart and do it every 3-5 gallons. s for polish, I use Autosol (metal polish).

Carb - polish the needles, go easy on it
Piston - polish the top of the piston, DO NOT polish the sides!!!
Cylinder head -polish the inside of the head
Sleeve - polish the outside (NOT INSIDE) of the sleeve till its gleaming
Crank - polish the whole crank till it gleams
Conrod - polish till it gleams

You can use a dremel as to hand polish will take too long. Remember to oil everything as you are assembling the engine. As for after run oils, do not waste money on the branded stuff RC cars use, just get light air tool oil, light machine oil or even auto transmission fluid. Its heck of a lot cheaper.