How to Ensure That Your Automatic Transmission Fluid Is Properly Changed

Most engineers recommend that you service an automatic transmission from time to time, but they may not tell you that a simple exchange of fluids is not sufficient. In other words, it's not enough to open the drain hole, evacuate the fluid, and then replace it until the dipstick shows that it's full. Why is this only doing "half the job," and what should you consider instead?

Fluid Trapped in Place

Due to the design of an automatic transmission system and, in particular, the torque converter, a lot of the fluid will be essentially trapped in hard-to-reach places when the system is not in motion. When everything is moving as it should, the fluid will circulate and will inevitably pass the drain hole. But this is no good when you are trying to drain with the vehicle in a static position, and this means that some of the old or degraded fluid will invariably remain in place.

The DIY Option (Care Required)

It is possible to overcome this problem at home, so long as you have a lot of patience, exercise due care and have an assistant to help you.

To begin with, you will need to elevate the car and place it on four sturdy axle stands. You will then need to open the drain hole and catch the old fluid as it exits while removing the dipstick or opening the plug to allow you to add more fluid.

With great care, you will need to start the vehicle in neutral while getting ready to add fluid. Your assistant will then need to sit in the driver's seat and carefully select the gears (including the reverse). You should then add new fluid at the same rate as the old lubricant is draining into the catch pan. As the system will be turning, it will automatically pump the old fluid out while you replace it with new instead.

As you can see, this is quite a complicated job, and you will need to be very careful as don't forget, the road wheels will be turning while you are underneath the vehicle.

The Better Approach

Most people in your situation will want a much simpler and more professional solution, and the good news is that your trusty mechanic can perform this task more easily. They'll have a machine that will be connected to the transmission system and can automatically flush and clean the torque converter. Have a word with your mechanic to schedule that appointment.

For more information on automatic transmission services, contact a professional near you.

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