I use 15/40 delo in my 2001 powerstroke, with
oil driven injectors . The reason for this is 15/40 delo does have anti foam additives . All I can tell you for sure is when I change the
oil, it acts like I just gave it a tune up.I use it in my 427 stroker to and see 6500 rpm often. I change it every two months or, 2000 miles, sometimes sooner. Never had a lubrication problem. Chevron uses high grade base stocks in their diesel
oil ,it is good stuff.