on the 4.0 I hook the scanner up so I can see the fluid temp , needs to be checked between like 80-120 degrees. When the temp is in spec there is a little torx screw in the pan that you take out. You have to pump fluid up into that hole with a fluid pump and a fitting. Pump it up in there until fluid runs out ....once it starts to run out let the excess run out then put the plug back in.