Well, I'd trust Woody before I'd trust myself, but I'll throw this in.

I was very accurate in my temp reads when I needed to fill my tranny. I used a IR gun, and then used a real dipstick.

The tranny never quite shifted as well as it did before I changed my fluid. And now in the winter I get a big chirp from the tranny until the car is warmed up. Its not the s/c clutch chirping either, since this chirp will happen sometimes when already cruising and then pressing the gas to accelerate more.

So all I'm saying is be very careful....

Mercedes says measure at 80C, and say that can only be achieved by hard driving for a half hour or 45 minutes.

Those with grill mods may have an even tougher time reaching 80C on their tranny temps, and also with it being winter then maybe even tougher.