Ford Escort RS - Head gasket gone? - Tommk4

I noticed just the other day that my header tank Is full of "Mayonaise" the kind you'd associate with oil and water mixing and emulsifying.

However If I remove the oil filler cap its completely clean in the head and the oil looks perfectly normal.

Also the Engine was only rebuilt 5k miles ago.

Is this definately a blown HG or is there any other way oil could find its way into the water?

Ford Escort RS - Head gasket gone? - elekie&a/c doctor

Can't remember if these are fitted with an oil cooler/heat exchanger on the back of the engine,between the oil filter and block.If these leak,it is possible to get oil in the coolant.