I have an oil leak for sometime now and i'm starting to narrow it down, some back ground driver side valve cover starting leaking changed that with a cork gasket found that was not such a good idea. Removed that and changed with ultra gray rtv did this 3 times with the leak at the same place. Installed a new valve cover. leak still in the same place. Today installed a new dipstick tube and "O"ring still had leak in the same place. placed bag over dip stick itself and and drove truck for about 25 miles, bag was filled with oil. Does anybody have a suggestion as to what the next step would be I'm at a lose right know. Oil does not seem to leak when engine is at idle only seems to happen after it has been driven for a while.