Truck Repair: N-14 Bearing wear and pan leaks, gasket leaks, chevron delo 400

Question
Hello,
Is it common to see copper on the main and rod shells in as little as 220,000 miles? This is a 1997 N-14 525 plus and due to oil pan leaks I checked them first at 220,000 and replaced all and another oil pan leak occurred at 430,000 and again the shells showed copper so I replaced them again. It now has 511,000 miles and I change the oil and filters every 12-14,000 miles (chevron Delo 400), and oil samples show normal wear. When I bought the truck new, I was told by a Cummins rep that I should see at least 600,000 before any bearing checks should be necessary. I would like your expert opinion on this and also the commonality of the oil pan gasket leaks.
Thank you,
Will

Answer
Oil pans on high horsepower engines usually leak at the rear.They made a thick stiffner plate to go across the rear with longer bolts.Unless there is an oil pressure problem or cantamination the bearings are good.YES it is normal for some copper to be showing.Have seen engines with more than 600,000 miles & nothing been done to them.