Thanks for the advice guys!

I haven't been right into the building for a while and so am only talking about ARFs. The last model's engine has shot bearings and pumps out some serious black oil from the exhaust. Bonus about that is I can see exactly where the oil is to clean it up! I always cleaned it with windex though, after every flight and then more thoroughly at the end of the day. The covering still ended up lifting though and oil got to the wood. Mind you I'm talking about over a three year period.

I've mounted the engine inverted and have a pitts muffler for it, so the exhaust should be directed away from most of the aircraft. I've gone over all the seams with the iron and was advised to run a bead of estapol along them, which should dry clear.

I'm in the process of sealing the engine bay now with epoxy... you mention thinning it down which I hadn't planned on. Do you just thin it with Methalated Spirits?

Cheers again

Mark