* Water and oil don't mix: Oil is hydrophobic (repels water), but when significant amounts of water are present, they can create an emulsion – a cloudy, milky mixture. This is similar to how oil and vinegar behave in a salad dressing.
* Sources of water contamination: Several things can introduce water into your engine's oil:
* Cracked cylinder head gasket: This is a common culprit. A damaged gasket allows coolant (which is mostly water) to leak into the engine's cylinders and mix with the oil.
* Leaking head bolts: Similar to a cracked gasket, this allows coolant to enter the oil.
* Condensation: In humid climates or during short trips, condensation can form inside the engine and mix with the oil, especially if the engine doesn't reach its operating temperature often enough to evaporate it. This usually results in less milky oil, but it's still a problem.
* Failed PCV valve: A faulty Positive Crankcase Ventilation valve can allow moisture from the crankcase to mix with the oil.
* Contaminated oil: Less likely, but possible if water somehow got into the oil during filling or storage.
Important: Milky engine oil is a serious problem that needs immediate attention. Driving with water in your engine oil can cause significant damage, including:
* Engine damage: Water can cause rust and corrosion in engine components, leading to costly repairs or even engine failure.
* Bearing failure: Water can wash away the lubricating properties of the oil, leading to bearing seizure and catastrophic engine damage.
If you see milky oil, do not drive your vehicle. Have it checked by a mechanic immediately to diagnose the cause and prevent further damage. They will likely need to perform a compression test, coolant pressure test and possibly a leak-down test to pinpoint the source of the water intrusion.
