HELP - possible blown head gasket ????

[andystargate]

A couple of weeks ago whilst my car was in for MOT it overheated and all of the water from the expansion bottle was blown out.

The car was allowed to cool down, water system refilled and got rid of an airlock.   The reason we believe it over heated was due to the fact the auxillary fan wasn't working, which has now been fixed.

After driving 220 miles this weekend, on inspecting the water I found oil on the surface of the reservoir bottle.  There is no signs of water in the oil or on the oil cap and there is no white smoke coming from the exhaust.  Before I start pulling the head to bits to inspect the head gasket, could it possibly be a hole in the automatic transmission oil cooler part of the radiator?
Or
can the head gasket be gone and you only get oil in the water part?

Any advice would be much appreciated.  thanks   

[dubiez]

I'm not an e32 expert but I would have thought that the gearbox would have had it's own radiator?

[Rob]

The best and easiest thing to do to tell is buy a block test kit that reacts to the hydrocarbons in the coolant if a head has blown. Think of it like a pregnancy test kit for the car. If it stays blue things are good. If it turns straw yellow.....bad news I'm afraid.

It's an excellent thing to take to a car inspection pre-purchase too. I am nearing the end of my first kit and I've done 15'ish checks with it.

http://www.frost.co.uk/item_Detail.asp?productID=8682&frostProductName=Block%20Tester