What causes engine oil emulsification?

I changed the oil in my car, ran an engine flush, drained it and then put in new oil. However, now the oil has that awful emulsification - how did this happen? There was absolutely no emulsification in the old oil. It's a high mileage 4.0-litre straight 6 petrol engine.
The main reason for oil emulsification is that coolant has mixed with the engine oil. This is commonly down to a failed head gasket or cracked cylinder head. We would suggest that you carry out a compression test to find out.
Answered by Alan Ross on

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