>> I consider steel wool a fine abrasive, how does it enhance a oil or wax finish and not leave scratch marks????
Obviously, steel wool and non-woven abrasive pads are abrasives and smoothing a surface involves scratching the surface. The key is to create ever smaller scratches until they become invisible. In general, 4/0 steel wool and gray scotchbrite rubbed in the direction of the grain, leave such fine scratches as to be almost invisible. That's what happens as you go from 400 to 600 to 1200 sandpaper followed by a polishing compound and a swirl remove. Each is an ever finer abrasive until it gets to the point where the surface looks glossy.
OK, what's that mean as far as using an oil/varnish finish. First, understand that an oil/varnish finish is intended to be an in-the-wood finish that leaves the look and feel of the wood. It's not intended to produce a super smooth gloss finish. Nor are then as durable as some other finishes. If you want gloss and/or durability, forget the oil/varnish and use a film finish like varnish, shellac or lacquer.
There are three application techniques for an oil/varnish. The first coat is the same for all. Apply the finish, let it set for 20-30 minutes and then wipe it as dry as you can. Let it dry overnight. The next steps are different. One maintains the most natural look to the wood. The other two impart a somewhat soft glow luster and a somewhat smooth feel to the wood.
The first is to just apply another coat of the oil/varnish just like the first, let it fully dry for 5-7 days and you're done.
The second, is to apply the second application using 4/0 steel wool or 400 W&D sandpaper creating a slurry which files the pores, wiping lightly after 30 minutes and letting it dry. After 7 days you can apply a paste wax. The last technique is to do the first coat as above, then do the second step above, let it dry and then, not using wax, rub the surface with 4/0 steel wool or gray scotchbrite. This will give you a somewhat lesser glow and a very natural look to the wood.
The only way to know what you like or to see what looks better on your project is to test out the options. There's no magic here. Oil/varnish products are all pretty similar. While the Behr contains only a very small dollop of real tung oil, it is really no different than most of the other faux Tung Oil Finishes". Making your own really gives you a much better finish.