Volvo dealers are among the most ignorant when it comes to oil.
Many of Volvo's reliability issues can be traced to the stupidity of Volvo dealers, who are notorious for using the wrong specification oil in the warranty, and non-warranty, Volvo cars. In 2001-2005, Volvo dealers were using bulk Castrol, which didn't meet Volvo's own specifications, because Volvo North America told them to!!
Actual conversations with a Volvo service advisor:
"You can't use synthetic in that turbo car, it causes the turbo to leak, that's why we use regular oil"
"You don't want that 0W40, it's way too thick, PLUS, it's too thin on start up, there's no way for the pump to build pressure with a zero viscosity, you'll wear out your turbo with that oil."