Other, less likely possibilities include:
* Cracked cylinder head: A crack in the cylinder head itself can also allow oil and coolant to intermingle. This is more severe than a blown head gasket.
* Cracked engine block: Less common than a cracked head, a crack in the engine block can also lead to oil and coolant mixing. This usually requires a major engine repair or replacement.
* Oil cooler failure: Some 4.2L V6 engines have an oil cooler integrated into the engine. A leak in this cooler can allow oil to enter the coolant system.
It's crucial to note: Driving a vehicle with oil in the coolant is extremely dangerous. The oil contaminates the coolant, hindering its ability to cool the engine, potentially leading to overheating and catastrophic engine damage. This also means your engine is likely losing oil and coolant, which could cause further problems.
You should NOT continue driving the vehicle. Have it towed to a qualified mechanic for proper diagnosis and repair. They will need to perform a pressure test on the cooling system and possibly a compression test to pinpoint the exact cause of the leak.
