I'm going to change the fluid in my Boxster S 6 speed - do it twice?

[steved0x]

When I changed the rear diff oil and the transfer case oil in my Toyota FJ Cruiser, I picked up about 1 MPG highway, which was a nice bonus and fairly significant, since I went from 16-17 MPG to 17-18 MPG.

I bet you will see an improvement.

I was wondering the same thing, since at my next change I am going to Millers CRX 75w90 NT, and I would like to flush out all the current oil, but that will probably be impossible. What I will probably do is take it for a little drive and get it nice and warmed up, and then get it home and jack it up and start draining the old oil while it is still warm. Maybe that will help more of it drain out, and that is probably as good as I'm going to be able to get it...