BMW: BMW Automatic Transmission, transmission oil cooler, 1997 bmw 318ti

Question
I have a 1997 BMW 318ti with automatic transmission. After driving for about 30 - 60 minutes, the transmission starts making a whining noise. A transmission warning light comes on on the dash and the car shifts roughly. There is no BMW service in my area (I live on an island in the Caribbean). Yes, I know I should have stuck with my donkey, but I figured a beemer would be as reliable :).

I know this is not the car you are familiar with, but if you can suggest what I need to look for, I would appreciate it. I am planning on changing the ATF and the filter in the transmission on my own. Do I need to change anything else?

The car works fine when the transmission is "cold". Should I be considering changing the transmission oil cooler?


Regards

Griff

Answer
Griff,
 Sounds like you are right on the money.  Although I am not familiar with these cars "as much" as the older ones, I still know a little.  I would do exactly what you said, change the ATF and filter.  When the ATF is cold, it's thicker, or more viscous.  As the ATF heats, it becomes thinner an pumps easier.  The ATF is probably old, and broken down.  So YOUR cold broken down ATF is equal to Good ATF when it's hot.  I am not 100% sure this will solve the problem, but it's the best place to start.  
 Good luck with those hurricanes!
 Josh