Yes tobz, I papped myself as well. It should come with a warning light as well so that at least you know what the feck is going on.
The headgasket has been replaced about 5000 miles ago, so I dont think it is that. I noticed my oil level was VERY LOW so I nipped out at lunch to get some oil. At the same time I noticed a little puddle of oil underneath the car, so I think I've got an oil leak. Would low oil cause the buzzer to go off?
I havent noticed any sludge in the expansion tank.
Where is the oil likely to be leaking from...?