In the 15-16s Volvo recommends 0w20 due to the oil consumption issue that may develop. But I don't believe this applies to vehicles outside that window.
I'm a Volvo dealer and I have never heard a recommendation of 0w20 for the 2015-16 cars due to oil consumption. Perhaps after engine replacement if ever needed.
We (the dealer) were instructed to use 0w20 weight for the 2019+ cars and that was due to the gas mileage the 2019+ is rated.
In Europe, 0w30 or 0w20 is what is recommend for these cars and 0w20 for North America only because 0w30 is hard for Castrol North America to come by. So the "fix" for lack of supply was to use the 0w20 solely. 5w30, 0w30, 0w20, it's all fine.
Liquimoly (Euro oil manufacture) makes an official Volvo certified oil for the SPA cars in 0w30. They call it "Spec V" and is the only oil in the world (or at that time we're the first) to get Volvo's Official certification. I use this in my XC90 in 0w30.
As a side note, I run 0w40 in my modified S60 P3 (400hp) for the protection characteristics of that weight and to help combat the added stress my S60 creates due to the higher power level and 0w30 in my 2018 XC90. Most higher end sports cars use 0w40 like the GTR, M3/4, AMG for this very reason.
My personal experience with 0w20 is that A) it burns and shear too quickly for a turbo application and B) Volvo recommends 0w30- 0w40 Weights in Europe anyway because it's readily available and those weights are less volatile to fatigue from oil samples I've had taken from my past cars after track use.
At the end of the day, just do what the manual says and then there's zero chance of any negative fallout with your car and warranty if the needs arises. ?
