Q: There is a smell of oil in radiator. The coolant looks dark and muddy. I have 86,000 miles on the vehicle and it has never been flushed.
A: I would recommend having the radiator flushed and refilled with the proper antifreeze/water mixture (usually 50% antifreeze to 50% water). Hopefully the old coolant is your only problem. After you have it flushed, keep an eye on the antifreeze condition. If you have an automatic transmission where the radiator cools both the coolant and the transmission fluid, the transmission fluid could be leaking into the radiator. Some vehicles may also have an integrated engine oil cooler located in the radiator, but designed to keep the oil separate from the coolant (like transmission oil coolers). If the radiator reservoirs do not keep these fluids separate, oil could leak into the coolant. One last thing, oil in the coolant could also be an indicator of a cracked head gasket or other gasket that is leaking oil into the cooling system. Check the engine oil and transmission oil to make sure you don’t have coolant mixing with these fluids.