1) Get the owners manual, ebay, Volvo etc. "Everybody" pokes fun at these books but they do belong with your car, as part of your car, and besides they have some useful info.

2) Your engine and filter hold a little over 4 qts. (One reason I like the dual remote oil filter, plus oil cooler on the turbo, with lines etc the car holds well over 5.5+ qts (really 6) - the more oil the better, to a limit - but don't overfill your engine!!) If you put 5 in your engine it must be overfilled...watch for leaks and some consumption - but you should be borderline OK. What does the dipstick say?

3) Use the SAE viscosity and the API grade (or later) called for in your owner's manual.

4) As for brands, Valvoline Max is marketing crap. If you have no leaks, switch to synthetic. Amsoil is the best. If you stay with petroleum oil, change oil frequently, and use one of the long run diesel (and gasoline) rated oils such as Chevron Delo 400, Shell, etc