Indianapolis RC South

1. How often should After-Run Oil be applied to an engine?
2. How much oil should be used?
3. Where should the oil be applied?

Ideally after every time you have run your engine
A few drops..  Enough to coat all the internal parts
Through the Carburetor...  Spin the engine over a couple of time after you add the oil

(You can also use transmission fluid or Marvel Mystery Oil)  Transmission fluid has alot of detergents so it will help keep the engine clean..  Becareful not to add to much or it will smoke for awhile ;)

What about a four stroke? Should you place a few drops through the glow plug area and remove the muffler and place some oil there?

It's usually hard to get to the carb on a 4 stroke so I put few drops into the exhaust pipe and turn the prop backwards a few times  (or More) to get the oil into the lower end and intake. Be careful of fluid locking the engine and then forcing it to turn as you could damage the inside parts. Most fuels have a certain amout of after run stuff in them. I think it's more important to run the remaining fuel out of the engine before packing my plane up after a session.

I agree, it's very important to burn/run the remaining fuel out of the engine while it's still hot.  The nitromethane in the fuel, if any is left in the engine, will draw moisture into the engine causing the bearings to rust.

Disconnect the fuel lines first, then restart with the glow driver. 
When it quits, start it again, if it will run. 
Once it won't start any more, open the throttle and crank it over a few seconds - with the heat still on. 
Be sure to restrain the plane - or have someone else do it - just in case it does start up.

If you're not going to run the engine for an extended period of time - say over the Winter, then you might consider putting a drop of two of after run oil in and distribute it evenly.

I normally don't use after run oil as it makes the engine harder to start the next time.

YMMV...  Chuck

I can testify that running the fuel out the engine and using after-run oil works.  I have a miraculous Saito that started right up after sitting for 10 years.

Getting the fuel out is probably the most important component to preventing rust inside the engine. Our Glow fuel is hydroscopic and attracts tons of moisture...

Be careful about using after run oil on some 4C engines with pumps as it could ruin it, especially YS engines.