A second half penalty, the first at Deepdale for 13 months, finished off by Nicky Wroe, was added to by an injury time break away goal by Will Hayhurst to give North End a 2-0 win.
Wroe smashed the ball down the middle after Jeffrey Monakana's cross had been handled away by Jonathan Grounds and then Will Hayhurst scored from 40 yards as North End broke into an empty net after an Oldham corner to give the Lilywhites a win and another clean sheet.
The first half was quite a feisty affair, the chilly Deepdale skies often breached by a shrill from the whistle of match referee Scott Mathieson, with three bookings and a bucket load of fouls.
North End were playing a high-tempo pressing game and this was linked up with some nice periods of slick one-touch passing, operating a 4-2-3-1 formation, with John Welsh in for the injured Lee Holmes.
The best chance of the half came just after the half hour mark from the first PNE corner of the game.
Skipper John Welsh took it on the right hand side after a Stuart Beavon shot, moved back up alongside Jack King with a switch to 4-4-2 just five minutes before, had deflected off big defender Jean Yves M’voto. The ball in from the North End No.19 found Beavon with his back to goal, he hooked past a shot past a defender and it was cleared off the line by a Latics man.
The visitors main threat came from former Everton man Jose Baxter and his set pieces. From open play he spun and shot wide of the right hand post from 25 yards out on 36 minutes and then two free kicks in quick succession followed.
The first, four minutes before the break saw the only save by either keeper in the opening half; Declan Rudd clawing Baxter’s free kick out of the top right hand corner from 25 yards. Oldham had the ball in net from corner, but a clear push from the already booked M’voto meant the referee blew up and the defender was perhaps lucky not to see a second yellow brandished in his direction.
Five minutes after the break and North End thought they had the opener, Will Hayhurst curled a beautiful ball in from the left and Jack King superbly lofted a header up and over Aussie keeper Dean Bouzanis, but it came back off the post and the Latics custodian was able to scramble and grab it.
A double change with just over 20 minutes left saw Monakana and Cummins add to the North End fire power and immediately after John Welsh went clean through before being cleaned out, but the officials somehow said no foul.
But then a shock - a home penalty!
The first for 13 months as a clear handball from Jonathan Grounds from Jeffrey Monakana's cross was seen and given by Scott Mathieson.
Nicky Wroe stepped up with 12 minutes left and drove the ball down the middle to give the Lilywhites the lead.
Bouzanis made a quite brilliant scrambling savge to deny Cummins a second with eight minutes left as his header from Wroe's cross was heading for the corner of the goal. The Irishman also met the resulting corner, but it was straight at the visiting stopper.
John Welsh hit a dipping volley with four minutes left to test Bouzanis as well, with no let up by the Lilywhites.
Three minutes of stoppage time were added on at the end and the opposition won a corner. Bouzanis came up and won another corner but North End cleared it through John Welsh and Will Hayhurst raced from his own box, outstripped an Oldham defender and slotted home from 40 yards out to round off another great win and to guarantee safety in League One.
PNE line-up: Rudd, Connolly (Monakana), Buchanan, Keane, Huntington, Wright, Welsh, Wroe (Mousinho, 85), Beavon (Cummins, 69), King, Hayhurst. Subs not used: Stuckmann, Garner, Procter, Mousinho, Foster.
Oldham Athletic line-up: Bouzanis, Grounds, Wesolowski, M’voto, Croft, Simpson, Byrne (Tarkowski, 38), Barnard (Miller, 74), Baxter, Reid (M Smith, 77), K Smith. Subs not used: Cisak, Brown, Montano, Mellor.
Attendance: 9,080 (854 away fans)
Referee: Mr S Mathieson