G'dy Jeff any good antifreeze that is compatible with alloy (thermostat housing is alloy) we use castrol coolplus at work in 50 % conc as most times when it needs a top up most people only use water and this still keeps conc levels up. A good supply of massey parts is bare co good price and good parts i dont know how they work over there but over here they have a network of dealers about 60 miles apart.Good luck