A transmission fluid circuit includes a transmission, a cooler, and a valve. The valve includes a housing, a spool and an actuator. The spool is movable inside the housing between a first position and a second position. The actuator includes a smart material configured to be activated in response to the temperature of the fluid exhibiting at least a first temperature such that the actuator is in a first state. The smart material is configured to be deactivated in response to the fluid being a sufficient number of degrees less than the first temperature such that the actuator is in a second state. The fluid flows from the housing to the transmission and from the transmission the cavity when the spool is in the first position. The fluid flows from the housing to the cooler and from the cooler to the transmission when the spool is in the second position.