I have a 2007 S40 T5 with 110k miles. I'm moving in a few weeks and will be driving from Chicago to Boston so I'm making sure everything is tip top before the journey. The transmission fluid has never been changed but there are no symptoms of a faulty transmission at all, it shifts smooth. Any recommendations on changing it or not?

Also any other recommendations? So far I have changed the timing belt/water pump, replaced front suspension, changed all rotors and pads, replaced and balanced tires.

 

No reason NOT to do a drain-and-refill on the transmission. As with any modern car with an automatic tranny, the tranny is the weak link, and the one thing that'll send it to the boneyard early.

Just drain the fluid, and refill with a skinny funnel into the tranny dipstick tube (a lot easier and safer than removing the fill port cap, which is in a "dirt collection hot spot", and can be a bear to get off).

You can just measure how much you drain out, and put that much back in, or just pour in four quarts (which is the amount that SHOULD drain out if it starts at the right level). You can see what that looks like at the 10:00 mark in
Easier than an oil change, and might just save a lot of wear and tear on your tranny during that road trip.