Many of you guys are forgetting about the stupid HEUI systems in these PSD engines. These are not your typical "small diesel" truck engine and certainly nothing close to a monster diesel used in a class VIII truck. They only hold 15 quarts of oil, not 15 gallons and the HEUI injection system beats the oil up at 2-3 times the rate a normal engine would.
I however, love 10W30 in my 05 PSD, and I tow heavy with it regularly with NO issues. Overall it starts better, seems to run smoother and gets slightly better MPG's than 15W40. However I will NOT ever go above a 7000 mile OCI in one of these trucks. Its cheap insurance for me to change the oil and keep the HPOP happy.