Do a search on these issues - there are many discussions on these forums for you to read about.

Change your transmission fluid ~50k miles.
There's a great article on bay13 about this : http://volvospeed.com/Repair/Transflush.php
I am not 100% sure, but I think your trans might need the 3309 fluid (as opposed to the regular Dexron III). Check that out before doing the flush.
DON'T use a power flush system!! Let the pump in the transmission do the work for you.

Change your bevel gear fluid ~50k miles.
There's a great article on bay13 about this too : http://volvospeed.com/Repair/AWD_bevelgear_diff_service.html
Don't bother buying the Volvo fluid because it's way too expensive. It takes 75W-90 Fully Synthetic GL-5.

Change your rear differential fluid ~100k miles.
I don't know if the rear end assembly in your car is the same/similar as the earlier models like my 1998, but here's the info I've amassed for my car, for your information:
You'll have to do this one with a 'suck it out, blow it in' method. 80W-90 Fully Synthetic GL-5. I pulled 100k miles out of the air really. It should probably be changed sometime, but many people go a really long time without touching these things. The whole rear end assembly in your new car is essentially the rear end out of an S90, which is a renamed 960. I don't know if it's different than the rear end from your 94 or not (you'd probably be able to tell us!?) and it's generally considered to be pretty bulletproof. That doesn't mean it doesn't deserve some good fluid every once-in-a-decade or so :)

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1998 V70 AWD Turbo 190k+