Owen has made only four appearances for the Red Devils this season, and none since November, since when he has been sidelined by a thigh problem.
Each goal he scored for Newcastle cost the club £1.3m in wages and his transfer fee.
Michael Owen: "I must admit, I don't think I am going to be one of the players who is still playing when they are 37 or 38 like Ryan.
"But I certainly think I still have another two or three years left in me.
"I listen to players in the dressing room; some players are struggling to get out of bed and complain about their knees or Achilles.
"I honestly can't resonate with them. I never get any pains like that.
"It is probably strange for people to hear that because they know I am injured.
"But joint-wise I feel great. I feel as though I can play, it's just when I get injuries, they always seem to be bad ones.
"My body feels as though it can play and my mind wants to and the aim is to keep going for at least another couple of years.
"In life, you have to make hard decisions. I have made some good ones and some bad, but in general terms I am pretty proud of my career.
"I still think I have another two or three years but where that will be is a question that the manager would be better placed to answer.
"I am exactly the same situation I was last year.
"Regardless what happens, you will never hear me grumbling about the privilege of playing at a top club like Manchester United.
"I have had some cracking moments. I have scored in cup finals, got the winner against Manchester City, scored a hat-trick in the Champions League and won the league.
"I am not concerned about what is around the corner."