A transmission fluid circuit includes a transmission, a cooler, and a valve. The transmission receives and expels a fluid. The cooler receives and expels the fluid to the transmission. The valve directs the flow of fluid received from the transmission to one of the transmission and the fluid cooler. The valve includes a housing, a spool and an actuator. The housing defines a cavity. The spool is movable longitudinally in the cavity between a first position and a second position to direct the flow of the fluid from the cavity to the cooler or the transmission. The actuator is operatively connected to the spool and includes a smart material which is activated in response to the temperature of the fluid in the cavity having at least a first temperature and deactivated in response to the fluid in the cavity having a sufficient number of degrees less than the first temperature.