this is not to start yet another war, but when I had my JD I had the dealer install Jd oil. When I got home and checked the oil it was black as the used oil.
So I used another oil and it is not as bad. I can go pull my dipstick o my bx right now and the oil is very clearn on the dipstick...
Case in point, if you want to know how dirty the oil is do an oil test. Untill then, you are guessing at every thing.
Same logic goes for gas oils. Some are quick and some are slower.