I have always used the cooler line, catch a gallon and then replace a gallon..

 

On many cars, the AT drain plug is magnetic, so doing a drain from there lets you clean the plug off too. But on these cars, the plug is not magnetic, so there's no real downside to the cooler line method. Upside is you can drain and fill as much as you like, not limited by AT pan capacity.

But I still do it by the pan, every 15k miles. I jack it up, on a 4* sloped driveway, and let it drain overnight to get as much out as I can. Close to 4 quarts, I think. A quick drain and fill on level ground is closer to 2 quarts, I think.

 

You might as well do at least three, that way most of the fluid is replaced, practically speaking. OEM Toyota fluid and gaskets are cheap at the dealer so really no downside.

 

gotta replace the filter so theres the second one...im hoping that will get rid of the whining noise at 1st and 2nd gear