About 25yrs ago, I used a mixture that worked real well..I forgot the ratio, but:
Boiled linseed oil
Turpentine
Polyurethane
1) Mix and apply to wood
2) Lightly steel wool after dry
3) Recoat and repeat above

The turpentine will evaporate, the linseed oil will penetrate to perserve the wood, and the polyurethane will seal the pores

After a few coats, you will have a nice finish, and know that the wood is well sealed..

The wood I did 25yrs ago still looks like it did when I finished it..

Just a thought...Shoop