What Causes the Milky White Substance on the Engine Oil Cap?

[EmersynLynn]

The milky white substance on the engine oil cap is caused by oil emulsification. Causes of oil emulsification: 1. Aging or poor sealing of the engine cylinder head gasket, allowing engine coolant to mix with the oil. 2. Damage to the engine oil cooler, leading to coolant entering the oil. 3. Driving through deep water puddles in summer, where water enters the engine interior through the crankcase ventilation pipe or air filter duct. Immediate inspection and repair are required if this occurs. Hazards of oil emulsification: After oil emulsification, the performance of the oil deteriorates. Effective oil film formation between internal engine components such as crankshaft bearings, camshafts, connecting rod bearings, pistons, and cylinder liners is compromised, leading to poor lubrication and accelerated wear of these parts. Emulsified oil contains excessive water and produces more harmful substances, which can corrode engine components. Additionally, the engine noise may increase, and the engine malfunction indicator light may illuminate.