Port Vale substitute Chris Cornes scored twice to earn his side a point.
Luke Beckett had put Oldham ahead by shooting home at the near post from Richie Wellens' pass for his 10th goal in 11 career appearances against Vale.
Cornes equalised from close range but Chris Killen restored Oldham's lead after Chris Porter set him up at Andy Liddell's corner.
Cornes had the final say with a firm downward header from George Abbey's right-wing cross to equalise again.
Port Vale: Goodlad, Abbey, Pilkington, Collins, Bell (Innes 83), Cummins, Dinning, Sonner (Cornes 53), Birchall, Paynter, Mulligan.
Subs Not Used: Brain, Rowland, Clarke.
Goals: Cornes 71, 90.
Oldham: Day, Tierney, Branston, Forbes, Scott, Eyres, Wellens, Bonner (Butcher 6), Liddell, Beckett (Porter 66), Killen.
Subs Not Used: Owen, Edwards, Smith.
Goals: Beckett 15, Killen 81.