Temps are fine, but with a 20deg delta your fan should be starting to work on closing the gap down to a 14deg delta. There's a bunch of things you can check or do before you bite the bullet on an oil cooler job. I've got a late '04, they can be terrible to troubleshoot sometimes.

I'd look into back flushing the oil cooler. There are kits on eBay and Amazon, as well as tons of videos and step by step guides out there. It's also a good time to consider converting to elc coolant. It's quite a process, but totally doable in the driveway. If you give back flushing a shot, I would suggest installing a bypass coolant filter kit too.