The car gets its first timing chain replacement in a few weeks...my question is will the tech have to drain the oil in order to roll a new one in?...I'm also having the oil pressure relief valve switched out of the oil filter housing...is the oil also drained enough out of there when the car is off for him to do that lil' bugger? I'm at the point where I change oil but will wait if he has to drop it all out to do the work. Thanx guys.