Mate has a rebuilt SR20, done around 600 miles after rebuild (new chain, tensioner, gaskets, piston rings, pumps, ported head) and noticed there is some oil on two pistons, other two are dry. There was also some oil in the lower part ob the intake manifold for those two cylinders.
Compression is the same as at the beginning, 150 150 148 148, he has changed OEM valve stem seals with supertech ones, but the problem is still there on those two cylinders after 10 min of running. What is the next thing he could look at, maybe valve guides? The engine has done 120k miles and the rebuild was done as a precaution, there was nothing wrong with it.
The hard starting when warm is probably from the oil leaking onto the pistons and when it starts, it fires up on 3 cylinders for a second or two, then the 4th one joins in.