05 - I have a 6mt xf in my garage in MN with 5k miles. The shifter has been just fine from the first day that i bought the car.

I plan on changing out my mtf with GM Synchromesh with Friction Modifier @ the first 2 wrench service, you may have to wait a while before that happens - sorry.

As for what fluid to use, don't take my word for it. Just read around, take my opinion as one of many...