What Causes Engine Oil to Turn Milky White?
2 Answers
This phenomenon is caused by water contamination leading to oil emulsification. Emulsified oil significantly reduces the oil film strength, failing to meet the engine's lubrication requirements. Immediate oil change is recommended. The primary cause of engine oil emulsification is coolant leakage from the radiator into the oil pan. Inspect the engine cylinder cooling system for cracks. Preventive measures for oil emulsification include: Warming up the engine: Always warm up the engine before driving and use the appropriate oil for your vehicle. Regular inspection: Frequently check areas like the air filter, especially in northern and humid regions. Air filter bypass: Direct the engine's breather tube to the atmosphere without connecting it to the air filter, but ensure the air filter hole is sealed. The breather tube should face downward and be securely fixed to prevent blockage and water ingress during rain.
Having been a mechanic for so many years, the most common cause of milky white engine oil is the mixing of water. This could be due to a coolant system leak, such as a damaged radiator or failed gasket, allowing liquid to seep into the oil pan and mix with the oil, forming an emulsion. Once emulsified, the oil's lubricating ability is significantly reduced, increasing friction during engine operation, which can lead to louder noise or unusual sounds. If left untreated for a long time, it can wear out critical components like piston rings and bearings. Checking is simple—just pull out the dipstick. If the oil appears creamy or foamy, stop the vehicle immediately and send it for inspection. Typically, this involves changing the oil and identifying the coolant system leak point. Don’t delay, or repair costs could double. Regular maintenance, such as cleaning oil passages and replacing the oil filter, can help prevent this. Developing a habit of warming up the engine to evaporate moisture is also beneficial.
