Hi Diesel,
Yes Sir, I know I come off a little on the brash side now and again, but I'm old and I've earned the right. :>)
I've been twistin' wrenches since I was 6 years old and always get a kick out of this "oil" topic and the way folks get caught up in it.
Fact is, this is a purely "human" choice and humans do get "attached" to their vehicles. I also noticed a few years ago, that after the sticker prices climbed above $20K for a silly pickup, folks then really started being "picky" about their "babies". :>)
But in all reality, that engine could give a fig less what kind of oil it is running.
It is innate; it is nothing but a chunk of iron and it has no opinions or feelings. It is a piece of machinery and at 200 degrees or better, after coming in off a four-hour pull on the interstate, when you pull the drain plug, believe me, all oils, I don't care what the weight, make or type, will come outta that pan having the consistency of water.
Like the Ford Tech said, sure, mixing oils is not the thing one would choose to do, not the perfect practice and not operating "by the rules", but its not endangering the truck in any way either and the level in the crankcase far, far out ranks the need for being "color and weight proper".
That fella just spent 4 hours under a hot, stinkin', knuckle bustin', swear-word enticing diesel and his very last thought before he closed the hood was to make darned sure that the oil level was correct and where it should be. I would have given the guy a tip. :>)
Now, just don't get me started on that silly "CPS" debacle. :>)
Allan