Coolant has entered the engine oil (Chevrolet Captiva 1)

Definition: Foamy or discolored oil, or overfilling the engine with oil, may indicate coolant is leaking into the crankcase. Low coolant levels, an inefficient cooling fan, or a faulty thermostat can cause "overheating" conditions that can damage engine components. Contaminated engine oil and a dirty oil filter should be replaced.

Cause	Elimination
Check the oil for excessive foaming or check for overfilling the engine with oil. Oil that is diluted with coolant may not lubricate the main bearings effectively, which could cause damage to engine components. See Noise in the lower part of the engine regardless of engine speed. The test is performed by testing the cylinder for possible leaks. During this test, excessive air bubbles in the cooling system may indicate a faulty seal or damaged components. Inspect when checking the compression ratio in the cylinder. The presence of a low compression ratio in two adjacent cylinders of the engine block may indicate the destruction of the cylinder head gasket. See "Compression pressure check" in this section.
The cylinder head gasket is faulty.	Replace the cylinder head gasket and components as necessary. See. Part 1C2, "Engine Mechanical - HFV6 3.2L".
The cylinder head is deformed.	Machine the cylinder head to the required flatness if possible and replace the cylinder head gasket. See. Part 1C2, "Engine Mechanical - HFV6 3.2L".
The cylinder head is cracked.	Replace the cylinder head and gasket.
The cylinder liner or engine block is cracked.	Replace these engine components if necessary.
There is porosity in the cylinder head or cylinder block.	Replace these engine components if necessary.