07-09-16, 06:05 PM
I can't see any way this could be oil related. The only time I had the clutch drag was when I failed to tighten up the sprocket cover properly, it worked loose over 30 miles or so until I couldn't get the bike into neutral.
It might be possible to have the fault come and go with temperature by setting the adjustment right on the edge of working when cold… but really it sounds like an assembly error of some sort. I'd have the clutch back out and triple-check everything is by the book.