The Gulls were always on top in a relegation six-pointer and took full advantage of a dismal home team who put in their worst performance under new boss Ronnie Moore.
Moore signed a two-year contract on Friday but it did not inspire his team at Boundary Park.
Oldham were inferior from the start as Torquay, with their fourth away win of the season, clinched victory through Matt Hockley and Adebayo Akinfenwa.
They could have scored as early as the fifth minute as Akinfenwa set the tone for his performance by beating defender Gareth Owen.
He fired straight at goalkeeper Leslie Pogliacomi who then made a fine save from Steve Woods.
Pogliacomi also denied Leon Constantine before blocking Akinfenwa and seeing the striker send his rebound over the crossbar.
Yet Oldham took the lead on 25 minutes as defender Dean Holden crossed to the far post and David Eyres ran in to hammer home an eight-yard volley from a tricky angle.
Torquay levelled four minutes before half time when Kevin Hill's through ball eluded the defence and was touched in from 16 yards by Hockley.
And the winner arrived on 49 minutes as Akinfenwa held off his marker to finish with real power from eight yards for his 15th of the season.
Constantine almost added a third moments later with a 25-yard screamer which hit the underside of the bar and bounced away to safety.
Oldham created very little and only went close to an equaliser when substitute Jermaine Johnson blazed over late in the game.