This is not on my truck, but on my Pap's 01 he just bought.

He changed the oil for the first time, and went on a short trip. Maybe 10 miles at the most. When he got back he noticed the oil was beginning to turn dark. The darkness was not consistent throughout the oil on the dipstick though. It looked like fresh oil, with darker oil mixed in. Its hard to explain.

Im just wondering why. The only thing I can deduct is that maybe he didnt get all the old oil out. Mayber there was still some in there somewhere, and it mixed in.

I do know that he did change the oil, and filter. And he drains the pan when its still hot.


Any ideas?

truck: 01 2wd 3500 auto, 100k miles

 

It's the old oil, totally impossible to get all of it out. That's part of the reason diesel oil tends to darken rapidly.

 

Could also be he had some sludge buildup in the truck. Maybe a previous owner was so great at doing frequent oil changes, or used low quality oil. The detergents in the new oil start to break that buildup down quickly and can cause the oil to darken like that.

It's funny, you can definitely see a difference in oil cleanliness vs miles driven with stop and go or short trips compared to long haul.

I did a cross country 2500 miles drive at the beginning of the month and the first thing I noticed was that the oil I changed in my truck the day before I left was still honey coloured when I got here. But 2500 miles running around home would definitely have darkened it much quicker.