The former United midfielder says Ighalo gives Solskjaer a genuine centre forward presence the rest of his strikers lack.
"He's different, he's a centre forward where as the other players can play out wide," he said.
"He gives you something extra off the bench when he's not starting. Centre forwards always want to score goals, he's done that everywhere he has gone. It's positive that he is able to stay because he has done well. He makes an impact when he's on the pitch."