Follow these instructions to keep the ATF cooler cleaner working properly:
Replace the two magnetic nonbypass spin-on filters after every 20 hours of use, based on the hour meter, or when you notice a restriction in the ATF flow.
Check the level and condition of the fluid in the tank before each use.
Replace the ATF in the tank when it looks dark or dirty.

Accessories
...
Tire and Loading Information Label
The label attached to the driver’s doorjamb provides necessary tire and
loading
information.
The tire and loading information label attached to the
driver’s doorjamb contains:
1 The number ...