I use 0w40 Mobil 1 all year round. I live in upstate New York, so our winters can get pretty cold at times, and summers can be in the 90s F for days at a time.
My V70 2.5T is almost at 190k miles. I add about 1 quart of oil between oil changes at 5k intervals and my car has been trouble-free since I purchased it at 107k miles in 2017.