[TCallas]

No. The white greasy substance on your engine oil cap is most likely water and oil mixed and is probably just from short distance driving. When your car is at operating temperature for a while, it is allowed to burn most of the moisture out of the engine oil. Is there anything strange looking other than just plain green or pink coolant in your coolant expansion tank (don't open unless the engine is dead cold)? Does the engine dip stick oil look normal? It should!