I'm using atf+4 but with Lucas Oil Automatic Transmission Fluid Conditioner
add in it and in both trans. and t-case it helps keep the varnish from biulding up when the fluid gets very hot. And if you think the trans. puts out heat what do you think the t-case is doing with only 2 or 3 qt. and no cooler and setting behind the eng. and trans.. That is from my trans. guy and I have taken t-case with and without the additiv and it does make a differts.