You mean Asian don't you.Loads of people have done a full fluid change on the jatco without problems.
It was over the weight of the trailer, but well under the 2000kg towing capacity of the FL1.I remember to saying previously the trailer was above the weight of the towing capacity of the FL1, as well as going up hill?
The insurance you're thinking of caused the TC clutch to shudder when it engaged. The 4th gear flare came later, after I'd changed the 2/4 duty solenoid and flushed the box with new fluid.