6-Pass Universal Transmission Oil Cooler Kit, Aluminum Tube and Fin with 5/16 in Hose and Mounting Hardware

Heat is the number one thing that kills an automatic transmission. Every time the fluid climbs past about 240F it starts breaking down, the clutches glaze, and the seals harden, and a factory cooler buried in the radiator tank is rarely enough once you tow, haul, or run the truck hard. Bolting an auxiliary cooler in front of the radiator is the single cheapest thing you can do to make a transmission live longer, and it is close to mandatory insurance any time you drop in a fresh or rebuilt unit.

This is a 6-pass tube-and-fin cooler built from aluminum alloy, measuring 15.66 by 7.5 by 0.75 inches, which is the sweet spot for most cars, half-ton trucks, and SUVs running 5/16 inch cooler lines. The fins pull heat off the fluid as it snakes back and forth through the six passes and air flows across them, so the ATF comes out cooler than it went in. Six passes gives you more cooling than a basic 4-pass without the mounting headaches of the big 8- and 10-pass units, so it fits where a bigger cooler will not.

It ships as a complete kit: the cooler, CPE hose rated for 145 PSI working and 900 PSI burst across a -40F to 257F range, the mounting bolts and rubber insulators, and printed installation instructions. Mount it in clean airflow ahead of the radiator or AC condenser, splice it into the cooler return line, and you are done in an afternoon. If you have a temperature gauge on the trans, you will watch the numbers drop the first time you load it up. Verify you have room to mount it and that your lines are 5/16 inch before ordering.