Fresh Fluid

DIY Auto Trans Flush & Fill

- Jay Kopycinski

THERE WAS A TIME WHEN REAL wheelers supposedly only drove stick. Automatic transmissions were some mysterious slushbox positioned between your engine and transfer case. Hit a rock with the transmission pan and all the magic fluid would leave said transmission, rendering your rig useless while buzzards circled overhead. Fast forward into the modern world where automatic transmissions are now very reliable and commonly in use by four-wheelers.

Hydraulic fluid is the lifeblood of an automatic transmission, and heat and contamination are the enemies of that precious liquid. In general, transmission fluid starts to degrade as temperature rises, and that degradation is said to be cumulative over the life of the fluid. In other words, fluid degradation can occur during short exposure to high heat or during long exposure to moderately high heat. Hence, it’s a good idea to change the fluid at recommended regular or severe-service intervals.

Most automatic transmissions hold roughly 10-14 quarts of fluid. If you simply drain what’s in the pan, you will typically only get about a third of the fluid out of the transmission. The torque converter holds a good amount, as do the transmission internals, fluid lines, and cooler(s). We’ll show you a fairly easy way to do a fluid replacement in your driveway without much hassle.