How to Change Your Car's Transmission Fluid

Extend the life of your engine by changing transmission fluid. It's much easier by using a special pump, and you'll save $100 in shop costs when you do it yourself. We show you what you need and how to do it.

Step 1.Buy a special transmission fluid pump

You should change your automatic transmission fluid according to the manufacturer's recommendation— whether that's 30,000 or 100,000 miles. This maintenance task will add tens of thousands of miles—which could be years of service—to a transmission's life expectancy and prevent repairs costing thousands down the road.

A transmission flush-and-fill from a shop will cost you $149 to $199. But you can do it yourself and save about $100. Draining the old fluid has always been a messy, ugly job. That's because it has meant lying under the car, “dropping” the pan—and then getting drenched in fluid. But here's a new way to change your fluid without going under the car and without spilling a drop. The procedure takes less than 30 minutes.

The trick is to work from the top, sucking out the old fluid up through the filler tube. Then refill with fresh fluid. A hand-operated vacuum pump makes the job simple and clean. You can remove one-third to one-half of the fluid from the transmission at a time. The rest will remain in the torque converter and the transmission cooler. So do the procedure three times at one-week intervals to replace nearly all of the old fluid. The little leftover old fluid will be diluted with plenty of fresh new fluid.

Some manufacturers recommend replacing the filter every time you change the transmission fluid. Go with what your dealership recommends. Note: But if your transmission pan is leaking, you should either “drop” the pan and replace the gasket, or take it in for service.

How to Recognize Old Fluid

New fluid is bright red. Old transmission fluid turns brown as it degrades—time to change.

Step 2. Insert the vacuum tube

Remove the dipstick and insert the vacuum tube until you feel it “bottom out” on the bottom of the transmission pan.

Step.3 Buy the Right Stuff

Carmakers have made major improvements to transmission fluids in the past two years. Contact the dealership parts department to see if your car requires a newer fluid. Then call auto parts stores until you find one that stocks it. If you strike out, bite the bullet and buy it from the dealer.