It was Redshaw's 16th goal of the season, although he started on the bench due to a groin strain, and cancelled out Alfie Potter's angled shot on the hour mark.
Bentley said: "Any away game when you go 1-0 down and come back to equalise at the end you're delighted with a point.
"It was a great corner in from Robbie Threlfall and Jack got in a great position and scored again to make it 16 for the season.
"The little fella's popped up again for us and we've come away with a hard-earned point."
Redshaw has now scored six goals in his last nine games, and Bentley added: "Jack's on fire at the moment, and the reason he wasn't on from the off is that he has a groin injury that we had to be careful with.
"If I'd played him from the start he could have pulled his groin and that would have been his season over.
"So we listened to our sports scientist, who said we could maybe get 20 or 30 minutes out of him at the end, and that's what we did, and it came up trumps."
He continued: "It was a tough, tough game for us. Oxford got their noses in front and they're a good side.
"We tried to play football but the pitch is shot here at Oxford. Sometimes we possibly tried to overplay because the ball was bobbling all over the place."