Mills first moved in August for an initial month. It was extended for a second month and has now been extended again to the maximum 93 days which means a return to Turf Moor on 13th November.
The left back, whose season long loan in 2012/13 automatically triggered a further two years at Turf Moor, made his Oldham debut on the third Saturday of the season in a 2-1 defeat at Peterborough.
He's since played a further seven league games, of which only one, at home to Port Vale, has been won, and he's also played two Johnstone's Paint Trophy games at Shrewsbury and Preston, both of which have been won.
His latest loan will see him available for a further four league games, starting at home tomorrow against Carlisle, and the next round of the JP Trophy against Notts County.
Source: Clarets Mad