Rotherham United striker Kieffer Moore added to his burgeoning reputation as the free-scoring Millers' extended their amazing goal record at AESSEAL New York Stadium.
The 6ft 5in hitman struck twice in four second-half minutes to seal the match for Paul Warne's men and take his tally to the season for eight, before late goals by Anthony Forde and Jerry Yates sealed the rout.
It was the third time in five home matches in League One this season that Rotherham have hit the visiting team for five.
The Millers were making hard work of beating John Sheridan's strugglers and the score was 1-1 until Moore hooked home on the volley after 74 minutes, following great work by Richie Towell and Ryan Williams, and then headed in Joe Newell's corner four minutes later.
The Millers are now up to eighth in the table after four wins in their last five matches.
Rotherham took an eighth-minute lead after Ben Purrington's stinging long-range drive had been superbly pushed away for a corner by Jack Ruddy.
Moore headed the flag-kick on to the bar and Michael Ihiekwe followed up to head home his first goal for the club.
Oldham, looking better than a team bottom of the table, equalised from a corner of their own 13 minutes later. Keeper Marek Rodak got a touch but couldn't deny Craig Davies as the Latics striker stole in front of the home defence to clip the ball into the net.
Needing a second-half response, the Millers stepped up a gear and the game turned on Moore's intervention.
After that, the Latics couldn't live with the home side and last-gasp strikes from substitutes Forde and Yates made the Millers the top scorers in the third tier.
Goals: Ihiekwe 8, Moore 74, 78, Forde 88, Yates 89 (Rotherham); Davies 21 (Oldham).
Rotherham (4-1-4-1): Rodak; Vaulks, Ihiekwe, Wood, Purrington; Potter; Williams, Towell (Forde 81), Frecklington, Taylor (Newell 62); Moore (Yates 84). Subs not used: O'Donnell, Ajayi, Cummings, Clarke-Harris.
Oldham (3-5-2): Ruddy; Edmundson, Clarke, Gerrard; McLaughlin (Dummigan 33), Byrne, Gardner (Omrani 62), Bryan, Nepomuceno; Obadeyi (Menig 62), Davies. Subs not used: Placide, Banks, Hunt, Fane.
Referee: John Brooks (Leicestershire).
Attendance: 8,250 (825).