My 1996 E320 is due for a transmission fluid and filter change. I've already purchased a filter/pan seal kit, but I'm not certain which type/brand of fluid is the best. Is Mobil 1 synthetic ATF acceptable or is there a better option? I'm also considering the addition of an aftermarket plate-type transmission cooler since I live in steamy St. Petersburg, Florida. Is there any reason why I shouldn't install it?

Chris