Originally Posted By: tomcat27
the oil pickup screen is very fine and has been known to clog with sludge. google it for more info.
This exact thing happened to my good friend's 2001 5.2 Ram. Fortunately, he caught it very early - he started losing oil pressure, knew something wasn't right, and dropped the pan. Pickup screen was so caked full of sludge I don't know how the pump was able to suck oil through it.
For fear of rebuke, I won't mention the motor oil he typically used... that may or may not have played a part anyway. But suffice it to say, I would be careful.
Some oils are known for their cleaning ability. I'd use one of those.