Toronto and Oshawa are not very far apart at all. They're so close that I consider Oshawa to be part of the Toronto area. One of the reasons they moved to 1580 was that they could raise their night power to 10 thousand watts. When they were previously at 1350, they could be heard in the daytime in Toronto very well, but not at night since they had to power down and switch antenna patterns. They are non directional now, and should be a fairly regular catch for you. Aparently they're pretty widely heard. You may have heard the mention of an FM signal at 107.7 which is very low powered at 200 watts and really is meant to supplement their signal in the downtown core in the office buildings. It barely covers the city on FM, if at all, at least in my experience.