BMW 523i E39 overheat problem

[78dude]

My good friend have an E39 523i who have not been used for some time now so today he manage to get a new battery for it and we did some TLC to the car and took it out for a spinn.
The problem we got after some few miles one the road is that the engine overheat, and it have now an issue that I was able to find mayonese under the oil cap after it had overheated. There is still coolant on the engine and I also discover that the viscouse fan clutch is also broken on it as well...

So my question is, will this engine only need a full service incl sorting out the coolant on it (exchange waterpump, thermostate and the clutch to the fan) Or is the head gone on the car?

[Omi]

All-alloy engine... If it has overheated badly, especially if it is the revised engine with the steel liners, then the block may have sunk around the liners and might be scrap metal.

Oil/coolant mixing is almost definately a head gasket, so just get it off and have a look.