I normally think thank most additives are a waste and possible even harmful but this ATF additive called Lubegard ( red bottle ) which may be worth using . Sold at NAPA and online at www.bulkpart.com

http://www.lubegard.com/automotive/trans_atf.html

Also adding an additional ATF cooler is never a bad idea and really a must for towing and mountain driving (see Long Mfg stacked plate ATF cooler at www.bulkpart.com )