Gardner has been with Wanderers since 1998 and his current deal at the Reebok Stadium runs out this summer. Having been sidelined for much of the season with a knee problem and then loaned out to Preston, the 32-year-old Jamaican has featured in Bolton's last four games as Coyle assesses him.
The manager recognises Gardner has been a great servant to the club but insists he will have to make a "football decision'' about the player's future.
"I have given Ricardo that game time to try and be fair to him,'' Coyle told the Bolton News. "He has been an outstanding player for the club. I like to think I am loyal to my players and I want to make sure I give them the opportunity.
"I told him I would give him game time to try and earn a contract. Now I have to sit down with him and make a decision. I will take all the emotion out of it and make a football decision.''
Gardner hopes he can extend his time at Bolton, but for now is simply focusing on Wanderers' run-in, which concludes with Sunday's home game against Manchester City.
"I don't even want to think about my contract, I just want to go out there and help my team-mates get the win we play each game for,'' Gardner said.
"I haven't spoken to the manager yet but we'll see what happens at the end of the season. It would be great to get a new deal and push on from there but at the end of the day it's up to the manager. I'd be pleased to stay on here.''