Check your thermostat and crankcase breather. If it has had a lot of short trips you can get a buildup of moisture in the top end but not usually much. If your thermo. is not closing then your engine never gets hot enough to burn the crud out. Take it for an extented drive and if that does not get rid of it then you might be burning coolant(ugh).
An oil analysis will tell you that or check the tail pipe on a cool day. If you are burning coolant you will see a lot of vapor out the exhaust and it will smell like burnt antifreeze.
82 300SD 100k
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