I don't bother to run the engine, Simply apply starter motor and flood it with fuel. then drain the fuel. All the nasty's should be out and all thats leftis the methanl with oil.

The methanol wil evaporate over a few hours leaving just the oil.

However Methanol contains oxygen so it can also promote corrosion if left behind for too long. At the end of the day, there is no fuel proof method to prevent corrosion entirely. On Planet Earth, water is everywhere