Current QPR boss McClaren, who helped coach the Norwegian and his team-mates to a historic treble as Sir Alex Ferguson's assistant in 1999, says Solskjaer has been "unbelievable" in the job so far.
"I think everyone was astonished at the appointment," McClaren told Sky Sports News. "(But) I know Ole well. He's a thinker and he's intelligent.
"He's a very good communicator with players. He's come into a situation where some people said he had nothing to lose - but he had everything to lose.
"No pressure? There's enormous pressure. It's one of the three biggest clubs in the world, so that's pressure in management. You put pressure on yourself because you want to do well, and I know Ole's ambitions.
"I think he's exceeded all expectations. They've played exciting, attacking, Manchester United old traditional football. And if it continues to work, I think Manchester United will have an easy decision to make at the end of the season."