After trying every tip in every single video I have found for the problem of squeaky treadmills, I was finally able to fix my Sole F85. I have tightened and lubricated every nut and bolt on this thing, and it has still been squeaking badly. But after tightening and lubricating the screws that hold the deck in place, it's finally silent!

I'm posting this video in the hope that it could be of use for someone else that have the same problem.