Hi Vince.
Unfortunetly it sounds like it may be the cylinder head gasket that has failed. To check this you can buy a DIY test kit that detects exhaust gases in the cooling system ,using coloured fluid that changes colour when exhaust gases are present in the coolant.
You could also try flushing out the cooling system to get rid of the oil that is there now, make sure you use an approriate cleaner from a good car parts shop ie Halfords etc. Best not to use any type of household detergent or cleaner etc. If the oil returns you must have an internal leak somewhere between the water and oil system.
Hope that helps
Good luck.
Tony B
January 2008