I was looking at a 13bt for sale, the problem is that the oil is a milky colour. The motor has been sitting on a shed floor for a while. The motor was running fine when pulled from car, so seller says.

Im guessing outer water seal gone?/??? Or could it be moisture from sitting a while.
Any ideas.

 

Probably the oil seal. "Running fine" and "No problems" are two very different statements. An engine will run fine with a lot of problems.

Expect a minimal rebuild (coolant seals & such). Apex seals could probably use replacement while you're in there.

-=Russ=-

 

How long is a "while"?
One year, it might be okay.
Several years...walk away; unless the motor was properly prepped for storage (i.e. oil squirted into rotors chambers and rotated every few months), rust (due to humidity by the hint of water in the oil you mentioned) would kill all the internal parts.


-Ted