I just had the oil changed at the dealer today in response to the message that started coming on last week. I last had the oil changed in Milan, Michigan. From there. I towed across the upper penninsula, around Door County, back to Texas, a number of short to medium trips around central Texas, and a trip to Eureka Springs.
At change time, the oil was still at the full mark (none had been added) and was perfectly clean in appearance, actually cleaner than the oil in my Buick.
Fuel mileage is still great. I towed the 25 Classic at 65 mph, mostly in cruise control, from Oklahoma City to south of Waco on a little less than 19 gallons of diesel. That's better than 15 mpg. If I slow to 60, I get about 16 mpg towing.
John W. Irwin
2005 Classic 28 "Sabre-Dog III"
2013 Silverado 2500HD Duramax/Allison LTZ
WBCCI #9632, TAC TX-10