I switched from Rotella to Amsoil synthesized oil in the Cat engine in my previous truck and it would use from 8 to 10 quarts in 10,000 miles. With Rotella it would only use about 2 quarts in the same amount of miles. It had the Amsoil in it when I traded it off. I'm sticking with ROTELLA and about a gallon of Lucas in this truck....
(it holds 41 quarts)
Mike