What would cause oil to gather in the cylinders of the head of a motor?

worn valve stem seals....


youll get a puff or 2 of smoke in the mornings,it will soon clear...cheep bits less than 拢2 but the head has to come offWhat would cause oil to gather in the cylinders of the head of a motor?
It could be worn valve stem guides, piston rings or head gasket. If it is every cylinder, major, just one or two less major. If you are mechanically inclined and have access to a combustion chamber guage, find said cylinder/s one at a time get a reading on the guage according to guage instructions. Take out the guage and put some Marvel Mystery Oil down into plug hole (couple caps or so). Reconnect the guage and get another reading if it goes up it's the rings. If the reading remains low and stays the same it is the valve guides, head gasket or another worse case scenario a cracked cylinder head. Don't worry about the mystery oil, great stuff and it burns off when the engine is finally started, don't mind a little smoke, unless it already does. Then it's the obvious, pay out time.What would cause oil to gather in the cylinders of the head of a motor?
If I understand the question it sounds like the valve cover or covers are leaking. Check this first. Is it using a lot of oil or did you just notice the oil?