How to change your automatic transmission fluid and filter

Transmission fluid... How often do you even think of changing your automatic fluid? Probably not that often, not until it starts to slip, but then its too late. To many people changing the tranny fluid and filter seems a little bit of out of reach for them to do....whether it seems too hard to do, or if its just the fact they don't know how to do it. In reality its pretty easy to do, although it might get a little messy, it shouldn't be hard at all.
This "how to" is aimed at automatic transmissions in general. Most mustangs that have autos are either AOD's, AODE's or 4R70W's, but this was made to give you a general idea on how to change the tranny filter and fluid on most transmissions.

1. First thing to do is to make sure you have the right tools for the job.
-You'll need the transmission filter and gasket, never use the old gasket or filter over.
-You'll need a drain pan big enough to hold all of the tranny fluid.
-You will need a ratchet and socket set, or at least a ratchet with the right sockets to fit the transmission pan bolts.
-You will also need the regular stuff to jack the car up...Jack, Jack stands, Wheel chocks.
-Also make sure you have enough of the right type of tranny fluid for your particular transmission.

On 4 wheel drive Chevrolet trucks you will need to remove the bracket that attaches the shifting cable to the transmission to be able to remove the transmission pan.

2. The next thing to do is to jack the car up, and put the wheel chocks, and jack stands in place. As always, never ever get under that car unless it is properly supported by jack stands, never get under a car only supported by a jack.

3. Place the drain pan under the transmission pan. A wide drain pan is very helpful at this point.

4. Find the right socket, and loosen all of the transmission pan bolts. Loosen them, but don't take them all out. At this point trans fluid should be pouring out. If its not then gently pry the tranny pan loose. Let it drain, then take all of the bolts out.
The reason you don't just remove all of the pan bolts at one time is because you need to let the tranny fluid drain, if you do remove all the bolts before it drains, you'll make a BIG mess.

5. Remove the tranny filter. Usually you have to remove two or three bolts to take the filter off. Make sure that you remove any gaskets that are between the filter and tranny too.

6. Clean up time. One of the biggest pains of doing a tranny filter is the fact that you have to scrape all of the old gasket off the tranny and tranny pan. So get to it! Gently scrape if off and clean everything up. Sometimes scraping the old gasket off is really easy, other times you wish you weren't born...LOL

7. Now that everything is cleaned off its time to install the new filter. Make sure that if you removed any gaskets that were between the filter and tranny that you replace it with a new gasket. Not doing so will damage the transmission.
Make sure you line up the filter with right holes or you'll be going nowhere when you're done.

8. Last thing to do under the car is to put the pan and new gasket on. Try to line up the gasket with the right holes on the pan and use a couple of bolts to hold the gasket in place. Usually just pushing a few bolts through the pan holes and then through the gasket will help hold the gasket in place until you are ready to put it on the tranny. Then hold the pan up to the transmission and tighten a few bolts. Make sure the gasket stays in place. Obviously.....tighten all of the bolts.
Note: Never use any type of glue or RTV on the gasket or as a substitute for a gasket. Why? You may be asking...because if any of the dry rtv falls into the tranny it will clog it up, causing major tranny damage.

9. Next thing to do is to lower the car, add the proper amount of fluid for your particular tranny and start the car up. While holding your foot on the brake put the car through all of the gears to let the fluid circulate. Put the car back in park and check for any leaks. Re-check the fluid with the engine running (at idle), with the tranny is park.
-Remember that not following all manufacturer's specifications, and instructions can/will cause severe transmission damage.