Cat C-7 diesel oil viscosity

I change the oil on my C7 once a year. In the farming, construction, and trucking business the 500 oil change is becoming a common practice. As the oils are much better these days. The early Cat engines has problems with the Heui pumps but I have not heard of to many problems with later ones. On our farm and motor home we have had 3 engine failures with their famous Brazilian made Cummins. Cummins have had their fair share of problems with their motor home engines. The 53 blocks, wrist pin failures, cracked or broken exhaust manifolds, 6.7's scoring cylinders and I could go on. I will stick to my Cat for now!;)