My Mercedes e320 has 186,000 miles on it. it is a 1996, I just purchased the vehicle so I do not know the history. every 15 or 20 miles or so, engine coolant level light comes on and I have to put coolant in reservoir. what is this problem due to? how can it be fixed, without incurring a steep cost.. what are the major issues it could cause should it not be fixed immediately?
First thing is to check your oil. If it looks like a latte then you've got a head gasket leak and it may already be too late. If it looks OK then first thing to do is check under the car after it's parked. If it's using coolant that quickly then there should be a puddle. If not, be sure to check the carpet in the passenger seat footwell, it could be a heater core leak. It's also possibly a leaky water pump relief valve. I'd recommend taking it to either a mechanic or a radiator shop and ask them to do a pressure test. This should make it easy to find the leak without overheating the engine.