Possible Headgasket Leak??? 1990 190E 2.6L

[lsmalley]

Yesterday I opened up my coolant reservoir to my 190E and saw that there was what appeared to be oil in the water. I immediately opened the oil cap and checked the oil dipstick, but that was fine, not milky, no weird smell in crankshaft. I examined the engine and noticed a small amount of liquid (not sure if its coolant or oil) on the ledge of the engine right next to the oil filter. I have not noticed any running issues with the car, no misfires, no exhaust smoke, or rough idling. After smelling the coolant it actually smells like the Bar's Leak pellets I put in a while ago to stop a leaking hose when I was out of town. But whats the deal with the water on the side of the engine ledge?