Check the two hoses that come from the engine near the oil filter to the oil cooler next to the radiator. If your car is older than about 25 years the chances are good that one of these hoses is leaking. If you buy these hoses from the MB dealer they will cost you your first born male child. Take the hoses to a parts shop that makes hydraulic hoses and they can make new ones for you. They are not fun to replace but when you are through you will never have to worry about your hands rusting.