wood grain filler

[f350ca]

Dallen you could try rubbing in the Tung oil with fine steel wool making figure 8 motions. The steel wool will cut the surface of the wood, the dust will be in suspension in the oil, some of it will pack into the open gain, the dried oil should then hold it there. This would be similar to the first stage of french polishing whee you use shellac.
A test piece is always recommended.