Went to the gas station to get gas today and decided to check my oil at the same time. The levels were fine, but the dipstick has some sort of residue on it; the stuff looks like rust but is wet and wipes off like mud. At the bottom of the dipstick where the oil is, there is some sort of gummy substance.

I just changed my oil yesterday and nothing looked particularly out of the ordinary (except for a small black deposits at one spot on the underside of the engine). The engine runs and sounds fine for the most part (my mechanic -- who specializes in Volvos -- tells me that the turbo sounds louder to him than most other 850s).

Any ideas what this stuff might be? Will it hurt my engine? How can I get rid of it safely?