Re: Transmission cooler
most of the heat in an automatic is generated by the torque converter, it starts making heat as soon as you start the engine(sliping). IMO as long as the fluid is warm enough for the pump to fill the converter, you're good to go. check with your local NAPA parts house for the largest trans cooler they have, its sized for medium duty vehicles. I put one on my p/up when the factory external cooler failed about three years ago and have not had any issues with the trans being to cold.