The thumping noise happens upon startup, and goes away pretty quick. The tapping gets worse as the engine warms up. Unfortunately I have very little history on the truck, so I dont know how many miles the engine has on it. But I do know that it's original. It wouldn't really suprise me if I have a rod bearing going out on it, but I hope not, as I am not in a position at the moment to have the engine pulled and rebuilt. I have 10W30 oil in it right now. Maybe I should go with something thicker?
