By now you all know that there is no such thing as any fluid on an automobile that lasts forever. Also you should know that there is no such thing as a sealed automatic transmission. Now what am I getting at here?

Automatic transmission fluid doesn’t last forever. Transmissions need to be flushed and that should be done every 2-3 years or 24-36,000 miles. But here is where you can get into trouble, because some shops sell you a flush but what they actually do is a fluid exchange and they are not the same thing.

Now a fluid exchange is for cars that have a dipstick such as this one does. And what they do is they have a machine that is attached to tubes like this. These tubes go down into the dipstick tube and the longer one pulls fluid from the bottom of the pan. The shorter one puts fresh fluid in. It’s just exchanging fluid. It’s not cleaning anything, it’s not really doing much of anything, and it may actually be detrimental to the transmission.

Now let’s raise this car up and take a peek at what a real transmission flush looks like. Now let’s see what a real transmission flush is. First thing up here we have cooling lines that come from the transmission to a cooler that is in a radiator or ahead of the radiator. Now what we do is disconnect one of those cooling lines and we take these two lines from the flush machine, one of them gets hooked onto the line that we just disconnected, the other gets hooked into the radiator. Now what we have done is we are diverging the fluid that normally circulates through those lines in the cooler, we’ve diverted it through our flush machine. Now there is no pumps or pressure or anything like that, it all relies on this normal circulation inside the transmission.

Alright, now, we put chemicals in it. We run the engine. The chemicals clean the inside of the transmission, including the torque converter, which is very very important. Those are things you don’t get with the fluid exchange. Now with the engine still running, we control where the fluid goes in the machine and so on and we can watch the color of it to see it get clean but what happens is that we trap all of the dirt that comes out of the transmission inside of the flush machine and we add brand new fluid.  And that’s the important part because you have to make sure that shop doing this job for you that they use a fluid that is approved for your car. Do this, you can double, triple, quadruple the life expectancy of your transmission. And if you have a question or a comment, drop me a line right here at MotorWeek.