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.
Use the exact weight your owners manual recommends. Any major brand will work just fine.
Premium is recommended, however I spoke with an employee at a Volvo dealer who said it is not necessary but you should use it every three fill ups just to keep the injectors clean. I still use premium all the time and i would recommend the same!
10w30
The 2010 Volvo XC70 runs on regular unleaded.
The 2013 Volvo C70 runs on regular unleaded.
The 2013 Volvo C30 runs on regular unleaded.
The 2012 Volvo XC60 runs on regular unleaded.
The 2014 Volvo XC70 runs on regular unleaded.