My girlfriend has a 1994 1.2 Vauxhall Corsa. The is loads of yellowy coloured gunk in the oil which I can only assume is water. However the car does not over heat and doesn't really use any oil or water. The only problem is that it does chugg a bit every now and then. Any ideas on the problem? I was thinking the head gasket but there are no oil/water leaks externally. any help/advice appreciated.