I've also been told..if it ain't broke don't fix it.That is, the transmission fluid.However,I've gone from being in the desert 4 last 16months & I'm sure the viscosity is becoming thick due to the dirt particles in the air.
How to check transmission fluid level?Better to flush or change(filter)&fluid? on 2005 Cadillac CTS
i rec you have it done by a pro,these can be slightly diff to deal with. there are alot of places that do it for a very fair price
if your car has a lot of miles on it and the tranny fluid hasnt been changed before it would be best just to leave it alone just make sure the fluid is topped up