I'm no expert but 9 qts sounds like way too much. what does your owner's manual say to use? I use that oil in my motorcycle, and it works very well, 10W40 is a higher quality oil than I normally put in my car but ok (its more expensive than 10w 30). Didn't know diesels took a different type. Check the oil dipstick, do you know how to do that? see where it is.
1985 190e 2.3