Hi Ian,
Why not simply do what Volvo advises?
Not that I suspect there is anything wrong with what you’re doing now, but the official approach has the added bonus of being cheaper and easier, since I now use and carry spares of the same oil for both the engine and SD.
Volvo’s change to this recommendation happened, as I recall, about 4 years ago…
Riyad
s/v Battuta
Vancouver, Canada
