Why is there engine oil in the radiator?
2 Answers
Reasons for engine oil in the radiator: 1. Cylinder liner damage: Under high pressure, engine oil can seep directly into the car radiator through gaps. 2. Radiator damage: Damage to the engine oil radiator or transmission radiator can also cause oil contamination in the radiator. 3. Cylinder gasket damage: If there is engine oil in the radiator and the high-temperature warning light is on, it is most likely due to a damaged cylinder gasket. Since the fuel in the cylinder is under high pressure for a long time, causing damage to the cylinder liner, the oil and water passages become interconnected in this state.
I've seen oil in the radiator many times, and the most common cause is a failure in the engine's internal seals. For example, if the cylinder head gasket is damaged, oil can leak from the engine block into the cooling passages. Another possibility is a cracked transmission oil cooler, as some vehicles integrate the radiator, and a leaking oil line can mix oil into the radiator. Additionally, a faulty oil cooler itself can cause leakage. Having oil in the radiator is no small matter—it contaminates the coolant, leading to higher water temperatures, radiator blockages, and in severe cases, engine overheating requiring major repairs. If you notice an oily residue in the radiator, I recommend taking it to a professional repair shop immediately instead of attempting DIY fixes to avoid more dangerous situations. Regular maintenance checks of the oil seals and cooling system can effectively prevent such issues, as safety should never be taken lightly.
