Two different posters asked me to give my two cents here so I just read through the whole thread and have several comments...
Gnoahhh has everything correct. He left out a few important details and several of his suggestions are not what I would suggest, but they are certainly not wrong.
I am pretty certain Skidrow and I went to the same charm school, and he also sticks to the facts
Oil is not a material that makes a good filler. It absolutely will shrink over time, telegraphing pores. It is absolutely unavoidable. As gnoahhh suggested, pores that do not telegraph over time were not filled with oil.
Oil finishes have the mystique on their side... it was THE finish for a very long time and it can be made very pretty... It was also expensive enough that it had to be used sparingly and kept far beyond its reasonable shelf-life.
And that was why "hand-rubbing" became such a big deal. Once it started to cure it required effort to work it into the wood.
No oil finish is truly waterproof and oil finishes after curing are more hygroscopic (suck water vapor out of the air as opposed to hydro- which refers to liquid water affinity) than bare wood.
Today's wiping varnishes are very easy to apply, simply by rubbing on a heavy coat, waiting 10-15 minutes and wiping dry, repeated many times.
Always make a sample board when possible with a cut-off from the work or even in the barrel channel. I have had many folks test a sanded in finish and none has liked it compared to properly filled finishes. The difference is almost always glaring, the larger-pored the wood is the more glaring.
Old time stockmakers and today's high-end guys get away with oil finishes through several conditions; they tend to use very fine-grained wood, they "cheat" a little with other fillers, or they use a wiping varnish labeled as an "oil finish".
"Oil finish" simply means the finish will look like an oil finish when done and can be applied like one. Many "Tung Oil Finishes" do not even contain Tung oil... they just look like it. As gnoahhh already stated there is no meaningful difference between tung and linseed, assuming they are of the same grade.
A couple random points... never use any varnish other than gloss. The matting agents (usually silica) do nothing positive for the finish. Rub out the finish to achieve the luster desired after the fact.
Filling a stock with a varnish or spar varnish and topping off with oil will look like an oil finish, be easier to repair than oil because the harder finish will ding less and be as easy to repair.
I am certain things were lost in the translation of Mr Pritchard's finish method. Using 320 grit paper between every coat would eliminate any build and create scratches which would be difficult to remove later. Rubbed oil layers are extremely thin and need sanding infrequently between layers, and with very fine paper.
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