Keith Newton
And go buy some more 4/4, when you need it. I don't think you are going to wrestle this wood back to flat, without reducing it to 1/2" on the jointer, turning most of it into shavings.

It probably will be fine for projects where you need 8/4, if you use good techniques, like sawing oversize, letting it settle, then straightening it at full thickness, or taking equal amounts off each face.

It is harder to find thick oak here sometimes, but I can always get 4/4.
You are just buying yourself head aches doing this.