Thanks, guys,
The oil looks fine, on the dip stick anyway. The only coolant leak I have ever found on this car is what comes out of the over flow hose by the the reservoir cap.

Is a Blackstone oil analysis the only way to derermine if there is coolant getting into the oil?

Any tips on trouble shooting the aux. fan on this '81 300 SD so I can determine if it's doing what it should?