Do you plan on extending the interval? sure looks like you can with ease.
From the looks of the samples I probably could, after all the true meaning of the "plus 50" is 50% over service interval. 10,000 mi. oc's are probably not out of the question.
I really can't understand why more powerstroke owners aren't using a 10w-30 grade,(duramax's also) almost everyone I talk to is not only afraid of 10w-30, but also leary of going up to 5,000mi. oci's. alot of guys are changing oil at 3,000mi. oci's
I know this subject has been hashed over before, but prior to the advent of 15w-40 all we used in all of our diesels was straight 30wt.(other that the detroits)with zero issues.