1.多久换一次:一般自己车的manual上有，有些没有，看repairmanual上也有，大致情况是30K或是24months,也有12个月的。
2.怎么换，多少钱: 首先要明确的是不同的车很不一样，大致分为两种：
a,.同换engineoil类似，transmissionfluid有一个drainnug，filter也是圆柱形，很像enginer filter.这种车换起来很容易，labor应该同换engine oil/filter一样，但是因为transimission fluid一般较贵，所以算起来大约10~20(labor)+20(4-5quarters)+ filter
注意：千万不要混淆engine filter/transmission filter，因为相似，常有把transmission fluid放光，以为放得是engineoil，然后加engineoil.这种情况下很可能把车给废了。（一个较简单的区别方法：对大多Chrysler和GM来说，engine filter在副座那边，而transmission filter在驾座这边。其他的车系不好说，欢迎补充）
b,.要拆transmissionpan的，别的不说，就这个pan拆下来也要下10多个螺丝，拿下来以后（过程中放掉fluid），才能下filter，另外一般pan里都有一个吸铁石用来吸金属屑，这个要清洗干净，安装的时候要把旧的gasket和sealer都去掉，换上新的，filter的gasket也要换新的，这种情况下，labor要高很多，估计是50~100(1hourslabor)+20(fluid)+>10(filter/gasket).这个gasket有很贵的，也有很便宜的，看车了。所以比较不同车换transmission fluid的价钱是没有太大意义的。
c.还有一些车，有专门的drainnug，但是filter在pan里面，这种车多数情况下车铺里就只换fluid的，如果开了pan换gasket和filter，价格参照上面的部分。
3. fluid的类型：常用的大致四种：ATF+3/4, ATF F，ATF A, Dexron III/Mercon. GM/Ford大多用DexronIII,Chrysler大多用ATF+3/4，其他较杂。最好参考自己的manual。千万不用用混。
4. 换transmission fluid不是flush transmission一般小车中transmission fluid有大约12-16quarter，但是每次换一般4-6 quarter.所以其实并不是真正地换了transmission fluid，flush不同，要有专门的高压设备，自己一般作不了，而且新车还可以作，旧车最好不要，flush旧车要冒废掉transmission的风险的。
Materials and Preparation:
1. Buy an automotive repair manual for your model of car to get familiar with your car, especially, the layout of transmission cooler and hose lines. In most cars, the transmission fluid cooler is integrated into radiator. The transmission fluid flows out transaxle into top of radiator through cooler’s inlet, and goes back to transaxle through cooler’s outlet at bottom of radiators. Some car may have opposite design.
2. To have your friend, spouse as an assistant .
3. 6 mm or 9 mm plastic tube few meters long, different size of plastic connector and clamp.
4. 12 to 15 quarts (bottles) of ATF. Use the type of ATF recommended by manufacturer in the owner’s manual. Misuse of wrong type of ATF may cause damage to your car’s transmission.
5. A large funnel with long narrow stem for filling ATF.
6. One large container (4 Gallon). It is better to have a transparent plastic container with graduation, allowing to estimate the fluid volume. One flat oil tray (1 gallon).
7. A floor jack (optional). Transmission cooler’s inlet is located in front of car under the radiator. It is relatively easy to access without jacking up the car. But you may want to lift the car up a little for more room.
8. Paper towel or rug for cleaning.
9. Screwdriver and pliers for removing hose clamps, if you can not use your fingers.
10. Before starting the work, make sure you completely understand the procedure.
Procedure:
1. Start the car, let it warm up for 5 min, and then shut the engine down.
2. Locate the transmission cooler’s inlet, and put the oil tray beneath. Then pull off hose line coming from transaxle. At this point there will be some transmission fluid coming out thru both ends of line.
3. Connect the transmission fluid hose to a piece of plastic tube long enough to direct the fluid into the large container. For extra safety you may also connect a piece of plastic tube to the cooler’s inlet and direct the tube into the large container.
4. Remove transmission dipstick, put the funnel on to the filling hole. Open the cap of all ATF bottles and put them in a place where they can be easily reached.
