I just drove to work and noticed when I stopped the engine was running quite hot, the guage was up at about 3/4. Checked the coolant and it's got a couple of fingers worth left in there. Doesn't look there is any mayo as i've heard it described in my oil. The coolant though has little bits of like sludge on the side of the tank, same colour as the coolant is. There has been no fluids of any kind under my car when it's been parked at work or at home and the oil and cooland looked fine this time last week, any ideas?