Its time to change it at 60000. A lot of people use redline MT-90. Motul 300 is talked about also. You need 4 quarts.
Jack car up, use jackstands and blocks.
Its easy to change. But you need a 1/2 socket. I got a 3/8 to 1/2 inch adapter. The 1/2 socket (yes, use the actual socket) removes the tranny drain bolt. The fluid comes out pretty quickly and shoots somewhat sideways, so be ready. The socket is on the drivers side of the tranny.
While it is draining (slowly by this time), remove the bolt in front. This is the fill bolt, and yes, it is horizontal. Buy 3 ft of 3/8 inch tubing and a funnel that can fit in the tube.
When the fluid is done draining, put the bolt back in. I don't remember the torque spec. I used a little grey RTV on the threads.
Now add 4 quarts through the funnel/tube. Remove tube, Torque bolt, go drive.