Up here, 'Suncor' Energy company owns the rights to the Sunoco name in Canada, and run stations under that name. With the recent merger with Petro-Canada, most observers are saying they will close down the Sunoco name use, and only sell gas under the better-known Petro-Canada name and station.
Sunoco does not sell its own brand of motor oil in Canada; all Sunoco stations sell predominantly Pennzoil motor oil. Suncor doesn't make its own brand of engine oil or gas in Canada; they just extract crude. So I suspect that SOPUS supplies the Sunoco stations with actual oil and gas; and Suncor just uses the name for marketing.
I know the situation is totally different in the US, where there is actual Sunoco oil and gas, just thought I'd chime in with the Canadian situation as far as I know it....