It's impressive how much oil can find its way down into the sump after a few weeks. I've taken to draining it and tipping it back into the tank...seems to make for much easier starting too.
How about a small bilge type pump to give a separate feed back to the oil tank? Should at least fail safe and simply not work once it packs up rather than stopping the oil feed to the engine. Don't know if anything suitable exists or how much of a pain it would be to plumb it in.
