allenmaty

Make sure you go to a reputable place or watch them! You will see a charge on your invoice for a filter, you could also ask to see the old filter.
And they can replace the filter and without needing to add fluid?
You will loose ~3-5 quarts changing the filter.

LordRipberger

So if you loose that much fluid changing how are you not basically replacing the ATF? Is there a way to just pour in more fluid or do you have to machine force it in like when they are flushing it?

allenmaty

There is depending on your transmission, about 12-15 quarts of ATF in there! Yes, it is a lot of oil if you change it all out, about $150 for Mobil1 ATF. The amount lost when changing the filter is just in the pan, the rest is in the torque converter. Unless your torque converter has a drain plug, you cannot drain it. Some do some don't depending on the year and model.

You add ATF in the same tube that your transmission dip stick is in. Just be careful not to overfill it, if you do you need to get a pump (autozone has them for a few bucks) and pump some out (though the dip stick tube). Been there done that!

Read the dip stick, it will have the instructions to let you know what fluid to use, whether to have it in park or neutral, or hot or cold temperature.

If the ATF is bright cherry red, there is no reason to change all the ATF, just add the amount lost in the pan and be on your merry way. If the ATF is dark red or brown, definitely have it completely replaced.