They are designed to run on 87. Most who I speak to run 89
Steep downgrades, when you need it to control your descent.
Any quality brand of 10W-30 should be fine. I use Castrol GTX.
Use only the weight recommended by Volvo and I doubt that they recommend 10w40.
You need to include a model. It's not going to be the same for a Volvo car as it is for a Volvo semi truck.
The 2012 Volvo S60 runs on regular unleaded.
The 2014 Volvo S80 runs on regular unleaded.
The 2013 Volvo S60 runs on regular unleaded.
The 2011 Volvo XC90 runs on regular unleaded.
The 2013 Volvo XC60 runs on regular unleaded.
The 2014 Volvo XC90 runs on regular unleaded.
The 2013 Volvo C30 runs on regular unleaded.
The 2012 Volvo XC90 runs on regular unleaded.