Brendan,
On a multi-grade oil, pour point depressants keep the viscosity 'thin' at low temps (0°), but it doesn't get 'thick' as it warms up....it just doesn't' get 'thin'. The parameters for measuring at 0° are different than at 210°.
Any oil will work in Old Number Seven! Some will work better than others...none will kill the engine. I'm not going to tell you if these comments are facts or my opinion. My bet is that this thread will go on for probably 50 posts, then the world will end.
Stuart
