A transmission heat exchange system for an engine comprising: a transmission oil cooler; a pump; a systems valve for receiving coolant, the systems valve comprising at least a first input, a first output and a second output, the systems valve being arranged to receive coolant at the first input of the systems valve and to provide that coolant to the first and second outputs of the systems valve, the amount of coolant provided to the first and second outputs of the systems valve being according to the condition of the systems valve; and a transmission valve for receiving coolant, the transmission valve comprising at least a first input, a second input and a first output, the transmission valve being arranged to receive coolant at the first and second inputs of the transmission valve in a ratio according to the condition of the valve and to provide that coolant to the first output of the transmission valve; wherein the pump is arranged to supply coolant to the first input of the systems valve and the second input of the transmission valve, the first output of the systems valve being arranged to supply coolant to the first input of the transmission valve; and wherein the first output of the transmission valve is arranged to supply coolant to the transmission oil cooler, and the second output of the systems valve is arranged to supply coolant to a further engine component, wherein the second input of the transmission valve is arranged to receive coolant from a radiator, the pump being arranged to supply coolant to the radiator, wherein the first input of the systems valve is arranged to receive coolant which has been heated by an internal combustion engine, wherein the systems valve comprises a first temperature responsive component, and wherein the amount of coolant being provided to the first and second outputs of the systems valve is determined by the temperature of the first temperature responsive component, wherein the transmission valve comprises a second temperature responsive component, the transmission valve being arranged to receive coolant at the first and second inputs of the transmission valve in a ratio determined by the temperature of the second temperature responsive component, and wherein coolant exiting the transmission oil cooler is arranged to flow near to the transmission valve, such that the temperature of the second temperature responsive component is at least partly controlled by the temperature of the coolant exiting the transmission oil cooler, characterised in that the further engine component is a cabin heater. a transmission oil cooler; a pump; a systems valve for receiving coolant, the systems valve comprising at least a first input, a first output and a second output, the systems valve being arranged to receive coolant at the first input of the systems valve and to provide that coolant to the first and second outputs of the systems valve, the amount of coolant provided to the first and second outputs of the systems valve being according to the condition of the systems valve; and a transmission valve for receiving coolant, the transmission valve comprising at least a first input, a second input and a first output, the transmission valve being arranged to receive coolant at the first and second inputs of the transmission valve in a ratio according to the condition of the valve and to provide that coolant to the first output of the transmission valve; wherein the pump is arranged to supply coolant to the first input of the systems valve and the second input of the transmission valve, the first output of the systems valve being arranged to supply coolant to the first input of the transmission valve; and wherein the first output of the transmission valve is arranged to supply coolant to the transmission oil cooler, and the second output of the systems valve is arranged to supply coolant to a further engine component, wherein the second input of the transmission valve is arranged to receive coolant from a radiator, the pump being arranged to supply coolant to the radiator, wherein the first input of the systems valve is arranged to receive coolant which has been heated by an internal combustion engine, wherein the systems valve comprises a first temperature responsive component, and wherein the amount of coolant being provided to the first and second outputs of the systems valve is determined by the temperature of the first temperature responsive component, wherein the transmission valve comprises a second temperature responsive component, the transmission valve being arranged to receive coolant at the first and second inputs of the transmission valve in a ratio determined by the temperature of the second temperature responsive component, and wherein coolant exiting the transmission oil cooler is arranged to flow near to the transmission valve, such that the temperature of the second temperature responsive component is at least partly controlled by the temperature of the coolant exiting the transmission oil cooler, characterised in that the further engine component is a cabin heater.