Yesterday after I drove the car from work to home about 4mile journey, I thought I would check the oil and the oil cap and I found a bit of Mayo on it. So this morning I checked the oil before I set off for work and topped with about a teacup full of oil, checked the oil cap and no Mayo. Got to work with same 4-mile journey and checked the oil temp which had reached 76C, checked the oil cap and the Mayo is there again. Is this most likely to be the head gasket or some thing? Last oil and filter change was done in December 05, I'm not loosing any coolant or any oil Noticed the Thermostat housi