Originally Posted By: Hethaerto
Originally Posted By: unDummy
Any full synth oil should be good. Quite hot in Ontario? Coin toss between your choices. Why not use XD3 or Duron 0w30?
I'd worry more about the transfer case(if AWD) and the transmission, and not worry as much about the engine.
Does the XC70 transfer case have it's own sump, or does it share with the tranny?
It does.
Volvo calls it the angle gear or bevel gear (depending on where you are looking).
The fluid turns a nasty brown color over time and should be replaced about every 50K miles. However, failures of the actual gear is rare, the biggest failure point is a splined sleeve that joins the bevel gear to the differential ring gear. This is usually caused by tires of different brands or tires of different amounts of wear being on the same vehicle (since people will replace single tires as they wear out completely).
The maximum recommended difference between tread depths on an AWD Volvo is 4/32".
Also, to the commenter about the transaxle. The Aisin Warner boxes that Volvo uses in these vehicles is bulletproof. As long as you do a flush when the fluid gets brown. It's expensive but worth it.
The GM transaxle found in the first generation inline six vehicles with a transversely mounted engine are the ones that have given Volvo a bad name with transaxles. However, these are rare and easily avoidable.