Hi everyone, would be greatful for any advice, my bmw 116d coolant tank is full of oil and no coolant its pure oil. There's no smoke from exhaust and the only warning from the car is coolant level low. I've never seen that much oil in coolant tank, is it definitely the head gasket or oil cooler, thanks in advance 

Morning Simon

Welcome to the Forum

If there is that much oil in the Header Tank it follows that water should be in the sump what is the Dip stick showing

I have never seen anything like that before ? by the stains around the top of the header tank it almost looks like it has been poured in there?

I have read of unscrupulous buyers distracting owners and pouring oil into header tanks then claiming head gasket failure and offering stupid low price to complete the sale. But thats OTT

I doubt the engine would be running well if that much oil is being lost to the cooling system. First I would carry out an oil change if there is water in the oil then you will see it around the oil cap as a creamy residue and definitely in the drained oil. If the drained oil is OK and the Oil Filler Cap clean next step is drain the coolant remove the header and clean it (if possible) with the coolant drained you should be able to check the oil cooler and its seals to the rad 

Good luck detecting the cause

Dave