I just checked the oil in my truck. The truck hasn't burned any oil but the oil itself is pretty dark. The oil was changed 4000 miles ago with Synthetic 5w40 and a Champ LFP780 filter. Is this normal to have your motor oil being pretty dark after only 4000 miles? Thanks Harley
It should be nearly dark afte half those many miles. It's not a gas engine, and diesels usually turn the oil brown fairly fast and eventually make it black. If the motor has a lot of sludge in it, it will turn the fresh oil black in 1-say 1,000 miles. Depending on the severity of the sludge.
Your oil is dark due to soot collecting in the oil. As your oil gets older it pick up more soot and gets darker. Best way to see if its still good - feel it and smell it. If it feels slippery like fresh oil, good. If it smells like oil, your good. If it smells like diesel fuel, dump it and refill. A quality bypass filter and quality oil will help eliminate this. Also, If you are concerned about how pure your oil is, there is always oil analysis. Check my sig for a link to info on all of the above.
