The biggest plus of the match for the Iron was the performance of Jonathan Forte, who is flourishing after being asked to step up following the departures of Paul Hayes and Gary Hooper.
He had a penalty claim turned away in the opening minute and should have scored after eight, but fired his shot at the visiting keeper Dean Brill.
After a strong start the Iron found themselves on the back foot, and Oldham turned their possession into a goal midway through the first-half when Djeny Bembo headed home from Richie Jone's cross.
United improved after the restart, and Forte grabbed the equalising goal. The Barbados international beat Jason Jarrett to the ball and placed it past Brill.
Oldham enjoyed some late pressure but pressure from Chris Dagnalll after 83 minutes fed Martyn Woolford, who scored the winner from 20 yards out.
The night also ended on a disappointing note for midfielder Sam Togwell, who only came on as a substitute but was sent off after being shown two yellow cards.