* Head Gasket Failure: This is the most common cause. A blown or leaking head gasket allows coolant to leak into the engine's cylinders and then into the oil pan, mixing with the oil.
* Cracked Cylinder Head: A crack in the cylinder head can also allow coolant to enter the engine's oil passages.
* Cracked Engine Block: Less common than a cracked head or blown head gasket, but a crack in the engine block can also lead to coolant mixing with the oil.
* Oil Cooler Leak: The oil cooler (if equipped) can develop leaks, allowing coolant to mix with the oil.
It's crucial to understand: Driving a car with milky oil is extremely risky. Continuing to drive with coolant in the oil can lead to:
* Engine Seizing: Coolant in the oil can severely reduce lubrication, leading to engine seizure and total engine failure.
* Internal Engine Damage: The abrasive nature of coolant can cause significant internal damage to engine components.
What to do:
1. Stop driving the vehicle immediately. Do not continue to drive until the problem is diagnosed and repaired.
2. Have the vehicle professionally inspected by a qualified mechanic. They can diagnose the exact cause of the milky oil using tests like a compression test, leak-down test, and possibly a coolant pressure test.
3. Do not attempt to fix this yourself unless you have significant mechanical experience. This is a complex repair requiring specialized tools and knowledge.
Ignoring milky oil can lead to extremely costly repairs or even a complete engine replacement. Get it checked out as soon as possible.
