Of course it is dirty. It is a scare tactic but they are probably not lying. You can do it yourself for much cheaper. You will probably have to buy one tool which you can find at Sears. I used Mobil1 Synthetic.

If you were local I would do it for you for much much less and only take 30 minutes.

I can't comment on the TB since I have not messed with mine yet.

Check here for pics. Differential Service - CrossfireForum.org Gallery

James