RE: after run oil
One of the engine manufacturers once remarked that 3 in 1 oil kept him in business (sorry, I don't recall which one). 3 in 1 is a penetrating oil with a lot of solvents. When these evaporate, a fairly hard gunk is left behind. The same is true of Marvel Mystery Oil. Either is fine if you are going flying next week. I use Rislone and have had engines stay free for years. If you run some castor oil in your fuel, there is less need for afterrun oil.
Jim