Poly is varnish. Just a urethane versus alkyd or other resin to harden the
oil.

I'm not a fan of slurry sanding. With red oak you can use an oil-based
filler which will give a fast and crisp fill, and can use it with your
oil-based stain.

"RKG" wrote in message
.. .

As far as varnish and poly being interchangable I don't know. I've only
been woodworking for just over 2 years since I retired and there is a lot
I
don't know about finishing.