Honda Repair: 1997 CRV Transmission, highway speeds, crv

Question
Craig,
my 97 CRV has 113k miles and I bought the car several months ago from a private party.  I've noticed that the car doesn't like to shift into lock up at highway speeds.  I've changed the fluid, using DEX III fluid.  It also has an inline tranny filter installed on one of the cooler lines.  I can feel it locking up and after a short while it will drop out and not lock back up.  Any suggestions?
Thanks, John

Answer
First off, never use dex 3 in a honda transmssion.  Always use honda fluid.  Can't explain why but you will have shifting problems if you use any other fluid.  Also, having one of these vehicles myself, they shift different than you may think sometimes.  Not sure why it isn't shifting into lockup though, especially since it should do that at like 50 mph.