- Oil cooler or transmission cooler failure: If the oil cooler or transmission cooler in the radiator fails, it can allow oil to mix with the coolant. This can be caused by corrosion, damage, or a manufacturing defect.
- Head gasket failure: If the head gasket between the cylinder head and engine block fails, it can allow oil to seep into the coolant passages.
- Cracked engine block or cylinder head: A crack in the engine block or cylinder head can also provide a pathway for oil to enter the coolant system.
- Porous engine block or cylinder head: In rare cases, a porous engine block or cylinder head can allow oil to seep into the coolant passages.
- Excessive blow-by: If there is excessive blow-by (combustion gases leaking past the piston rings), it can pressurize the crankcase and force oil into the radiator.
It's important to have the oil contamination issue in your 2001 Buick Century diagnosed and repaired as soon as possible, as it can cause serious engine damage.
