My 04. 5 600 was the same as everyone else's when it was new... . many were reporting that the oil turned BLACK very quickly. At about my 3rd oil change my oil stayed fairly clear, when it needed changing it was not black and I could easily see the marks on the dip stick. 3,000 miles ago I used Delo 400 and I noticed it was very BLACK at around 2500 miles. Smelled fine, truck running good etc... So after 3,000 I went to dealer and used one of my free coupon oil changes and so far still staying very clear. DO some oils / brands/ turn black quicker??? What would make the oil turn black all of a sudden??? I know diesels are known for this, but I just wondered why it would be pretty clear, then black, then clear again? Thanks! Oo.