Hi Wagoneer-
"Service Intervals" are 10,000 miles. Includes all the routine normal stuff: oil, grease, all filters, inspection of brakes, hubs, clutch, etc, etc. I use Rotella 15w-40 Dino oil. I have thought abt switching to synthetic oil and extending the service interval but that stuff is really expensive, and because the engine is approaching a million miles I like the idea of getting the old oil out and new stuff in. I drive this vehicle only abt 10,000 miles per year so this works out to an oil change in late fall each year before the snow flies (until I come to RTR in 2018!).
Yes, the motor is an inline six; a Cat C-15 (6nz) 550 hp. Runs like a top.
By the way, I always enjoy your posts.