[1retired06]

Originally Posted by Daryles

I have always changed the oil in my vehicles (gas cars) myself, until I got this big diesel truck. Never worked on a diesel before. I have been taking it to our local (an hour away) Ford dealership for oil changes. I have taken it to a local place when due when on the road.
Due to time constraints (we leave Tuesday on our next road trip, gone until October) I took it to our local "good old boys" garage last Monday.
I just noticed on the receipt they put 15W-40 oil in it.
Ford recommends 5W-30 synthetic in the owners manual.
I called them and they said that's what their supplier recommends. He said no problem.

Guys, I have NO experience with diesel engines.
Should I not worry about it this time and go with it, or change it???

I've read my times on this forum people recommending Shell Rotella.

I have always run 15W40. That is what Ford recommends for heavy use, like towing a fiver. You will see that in your manual and 15W40 is stamped on your engine oil cap. Rotella T6 synthetic is all I have ever used.