Saw 8 responses. All OK. However IMO and experiences I don't baby model airplane engines. I squirt some oil in one destined for storage and pitch it in the drawers (file cabinets and small chest-of-drawers). I had well over a 100 by last count a few years ago.
If I want to use one, I simply take it out and wash throughly with either wood alcohol, or rubbing alcohol depending on what's in reach or if engine is badly gummed up. May even remove backplate, etc. but get it fairly clean, oil it up with some machine oil/whatever is handy, and get it back together. I have many times picked out an engine that may have been in the drawer for well over 10 years and up to over 20 years, cleaned it up, set it in an airplane, choked it a few times, turn the prop over by hand several times, felt the *bump* and one flip has it running.
If you wish to really protect your engine, the best thing to do is use a fuel filter between the tank and carb, (catches that garbage the muffler feeds back into the tank) and to set needle for at least 700 RPM BELOW (Old sport engines I use 1000) the peak ground RPM. In addition use a suitable size prop. Not too small or too big. Too small simply over-revs. and too large lugs the engine at a low RPM that prevents adequate cooling fuel mixture to circulate through the crankcase.
After flying connect the fuel feed line to the tank overflow line. You can stop any leaks on the floor that way, and your muffler/engine does not get a case full of fuel should you point the nose down
Do empty the tank after a day's flying. The fuel will eventually corrode the brass tank lines. Oil congealing in the tank, in the carb, or engine crankcase can give you a fit for the first flight of the day. If you then start making big changes, well, the fits continue.
Don't worry about the engine too much except during the flying lean/rich/prop thing. You can easily wind up stomping pixx ants while the elephants thunder over your bod.!