I replaced the water pump and idle pulley on a whim(should have just took the belt off and ran it for a min) its not the water pump. I could almost swear its internal like crank bearings. um. the cap says to put 5w-20 and i put in 10w-30. can this be the culprit? it has 53,000 on it. or is this problem the reason this car was traded in? my plan now is to drain the new oil and pour in 5w-20 and a quart of dura lube. i really do not want to pull the pan off. any suggestions? it not the tensioner or the a/c comp. or the alt. or the p/s pump.