So, new to forum, new to duramax. I bought a 2001 to replace my 2001 8.1 because of the great gas mileage. However, the guy had been running fryer oil and I suspect running car oil instead of Diesel oil as the pan and valve covers were completely full of jello. My engine rebuilder says he has seen that happen before. But the motor ran fine, and has good oil pressure. I cleaned it all out, opened up the oil passages so oil doesn't overflow out the pcv's. Pulled the pan 3 times with oil change. Runs strong, but last time pulled pan, lots of gold bits and 3 pieces of bearing? bits. 2 about the size of little fingernail. Suspect it ran low on oil since only 1 gal. came out, the rest was the sludge. Dipstick said full. The guy had just changed oil, wonder what he thought when it only took 1 gal. to fill it? If it is main or rod bearing, probably already messed up the crank, so, do I just keep driving it and see how long it goes, then buy a used motor, or pull now? Rebuild will cost more than used???? Thanks in advance!