Keith, that image is also in TSB 05-16-06. I live by that TSB up here. Out of curiousity, what is your opinion on viscosities in these engines. I personnally believe in 15W40 in the summer because I believe with the amount heat these engines create, you need all the protection against thermal breakdown you can get. We have bulk tanks for oil and we switch our diesel oil to 10W30 in the fall and 15W40 in the spring. We are smack dab in the centre of the oil patch and have alot of customers that haul alot of heavy crap. I also see tonnes of engine oil cooler failures that I believe are related to thermal breakdown and lack of maintenance. By the way, that TSB also displays that 15W40 is preferred for trailer towing.