1995 Hyundai accent lsi with white smoke coming out of the back even when warm after the engine warms up the milky substance on oil cap disappears and oil is clean also coolant is fine no drop in leve?

The white exhaust and the milky substance is a clue you have a blown head gasket, it may be small enough you are not noticing a drop in coolant level but these things do not heal themselves. You can have a pressure test done on the head to determine of there is a leak.