Sorry, I just seen it was a good write up about soot. Things have change since we started driving a truck. Our old line haul trucks have 700,000 miles but that seems to the highest with out a new motor. We have a 3 minute idle timer before the engine shuts down without moving the truck or you go into over idle or shut down. The manual says 3-5 minutes and I do 30 stops a day, so that equates to at least 80 stop/startups. I already have coolant issues with 17000 miles and some starting issues too.

Ice road truckers use 0w30 oil. 10w30 is also starting to show up in the new trucks. Its a little thinner than the 15w40 so maybe a little more oil consumption but is strong enough for heavy duty operation from what I have read. http://www.gofurtherwithfs.com/Produ...ec%20Sheet.pdf

 

Bingo! In reality longer intervals have been in owners manuals for half a century. Ford had a 6000 mile recommendation in the early 1960's. By the 1990's most automakers were comfortable with 7,500 since oil chemistry was so much better by then. The only cars I owned with a legitimate 3000 mile interval were air cooled VW's that had no oil filter, only held 2.5 quarts and had poor temperature control compared to liquid cooled engines.