Funnily enough I was told exactly the same recipe as André; it works well, with the turpentine helping the linseed to penetrate the wood, or at least, so I think. It must be genuine turpentine though, not substitute.
Added later - I use terebinth as a drier. It's hard to find here in the UK apart from specialist outlets, but it's available over the counter in supermarkets just over the Channel, so I stock up when over there.