Another late goal from Nigel Clough's battlers made it seven unbeaten in Sky Bet League One for the Blades.
Like the previous game, substitute Chris Porter came on to turn in a Jamie Murphy cross to cancel out a first half goal from Oldham's James Wilson.
In United's last away game of the campaign, it was fitting that Oldham old boy Porter netted the goal that denied Oldham victory.
Following the victory at Port Vale, boss Clough made just one enforced change with Kennedy taking over from the injured Collins in the heart of the defence - teenager Dimaio took the available place on the bench.
The Blades were the more positive of the teams early in the encounter. Scougall ran into a wall of defenders and Brayford hooked over after Coady had challenged goalkeeper Rachubka in the air.
Oldham responded with a Clarke-Harris shot flying wide and then Howard pushed over a shot from Harkins from an acute angle, although the resulting corner brought the home side the lead. The set-piece was half-cleared but ex Blade Brown swung in a cross and defender WILSON, still forward, got ahead of his marker to direct a header past Howard.
The sides then exchanged chances. Baxter and Flynn both had shots deflected wide, whilst Dayton's effort was blocked by Kennedy and Clarke-Harris fired into the sidenetting.
As the half progressed most on the chances were falling for United. Scougall shot wide and over as he found space around the edge of the box, whilst on 31 minutes Baxter danced through the home defence but in a one-on-one situation his effort was saved by the legs of Rachubka.
Before the break the Blades did have the ball in the net but it did not count. Brayford's run and threaded pass found Coady, who slotted home but he was adjudged to be offside.
The second half kicked off with neither manager tempted into a change and Dayton was the first to attack - his shot looked dangerous before taking a deflection off Kennedy. Clarke-Harris and Maguire picked up yellow cards in separate incidents and a snap-shot from Brayford almost caught out Rachubka.
United were applying the second half pressure but Oldham were looking solid, looking to protect their own unbeaten run. On 66 minutes a Baxter free-kick resulted in Kennedy heading against the crossbar and Doyle's follow up was on target but blocked in a crowded penalty area.
Soon after a Maguire header from Doyle's cross was narrowly wide before Clough made a couple of changes, Porter replaced Coady ahead of Davies taking over from Flynn.
A rare Oldham attack saw MacDonald flick wide from Winchester's cross ahead of United's second half display being rewarded with an equaliser on 84 minutes. The goal was made by Murphy, whose run from the right saw him beat at least three defenders ahead of pulling back for substitute PORTER slotting home from close range.
Paynter replaced Baxter with five minutes to go and the momentum was with United, although former Blade Philliskirk shot into the sidenetting for the home side.
Three minutes of injury-time saw Murphy go on another run, causing untold problems for the home defence but this time Rachubka flicked over Doyle's shot, just seconds before the final whistle.
Oldham: Rachubka, Brown, Smith, Clarke-Harris (MacDonald 59), Wilson, Lockwood, Dayton, Kissock (Winchester 73), Byrom, Worrall, Harkins (Philliskirk 73).
Unused: Coleman, Dunfield, Millar, Byrnes.
Blades: Howard, Brayford, Maguire, Flynn (Davies 78), Doyle, Baxter (Paynter 85), Coady (Porter 68), Scougall, Murphy, Freeman, Kennedy.
Unused: Hill, McGinn, Long, Dimaio.