I wrote Volvo and ask about the factory fill for both oil and atf. Neither is synthetic and the oil is 5w-30. The Mobil atf for many newer volvo 5 speeds, aisan-warner transmissions, is atf 3309, which is not a synthetic. I would not use anything other than an approved atf for these transmissions. As a number of retailers carry this atf is can often be purchased for far less than the volvo brand atf. This may be the way to go for a flush. Good luck.