Volkswagen had things all its own way on the opening Sta Catalina to La Pampa stage, as Ogier went quickest and opened an 8.8-second lead over team-mate Jari-Matti Latvala.
Loeb was back in fourth, just behind Citroen team-mate Mikko Hirvonen, and struggling to find the right rhythm in his first World Rally Championship appearance for nearly three months.
But on the following 51-kilometre Asochinga to Agua de Oro stage, Citroen fought back, with Hirvonen and a much happier Loeb first and second fastest.
Loeb wraps up Argentina victory
Ogier lost 6.7s to Hirvonen and hit out at third works Citroen driver Dani Sordo, who he accused of holding him up.
Sordo had rolled his car due to a miscalled pace note, and was limping through the stage without power steering.
Ogier therefore heads to the lunchtime service 3.6s ahead of Hirvonen and 6s in front of Loeb.
Latvala struggled with extreme tyre wear on Ascochinga and fell to fourth, 23.5s from the lead.
Mads Ostberg is the best of the M-Sport Ford drivers in fifth, already half a minute behind. Both the Norwegian and team-mate Thierry Neuville struggled with windscreen wiper issues on SS2.
Sordo's incident leaves him nearly eight minutes behind the frontrunners.
Ogier pulls away in Argentina
Latvala elects to run last in Argentina