[motorcritter]

Temp drop depends upon size of cooler and location. Bigger is better, for towing or severe duty. The newer style laminar flow types are more efficient than the older tube-and-fin style. As noted before, don't run the add-on cooler as the sole cooler, plumb it into the existing lines, on the return line. Another 'mod' for cooler, more efficient transmission operation is LubeGard additive. It is the only stuff any OEM approves of, and it works. It's not a miracle worker, fix whatever ails ya, type of additive- but it does lower fluid temps and smoothes out shifting. I put it in every auto trans I have, or work on (except Frod MerconV units- it's a unique and highly-friction modified synthetic fluid)- the GM TurboHydros, the wife's Honda, my Benz gas-engine sedan and MoPar items (that need all the trans help they can get). All the other 'additives' range from useless to criminal- the proof is in the tear down before the rebuild. I'd always ask what got put in it, to try to 'fix' the progressively failing unit. Amazing what people dump into the most complex bit of engineering in the whole car!