The Gulls are currently being pipped to an automatic promotion place by Crawley Town on goal difference after the Red Devils beat Northampton 3-1 to leapfrog the Devon outfit, but Oastler insists that the race for the top three spots is far from over.
Oastler said: "All we can do is focus on ourselves and making sure that we win our games and hopefully everything will be okay.
"It seems to look like a two-horse race for third place now, but you never know what can happen in football. Shrewsbury are four points clear now, so you'd fancy them to go on and seal automatic promotion, so it is down to us or Crawley to join them.
"Whoever comes out best over the next three games will obviously go up, but we can only focus on doing our job first and then seeing whether it is good enough at the end of the season."
Torquay travel to Wimbledon on Saturday.