Join Date: Apr 2013
Location: North Dakota
Model: 1999 GL1500SE, soon to be sold 2007 GL1800 PA
i have been using Shell Rotella 15-40 in all my vehicles for many years. It is a heavy duty diesel oil but meets or exceeds all the specs for all the engines I use it in. I have been a auto mechanic and also my own motorcycle mechanic for many years. Show me how a engine knows the difference from one oil to another??? I run around 5000 to 8000 miles between changes depending on type of driving done on the vehicle between the changes. All my vehicles except the new to me 1999 GL 1500 SE have in excess of 100,000 miles on them and are running strong. Just like my cousins Cummins Diesel trucks.