Advice on refinishing walnut with tung oil

Hi Guys,

I have a black walnut box that as previously been finished with tung oil, to my mind the wood needs a couple more coats to even out the finish, particularly on the end grain. I also want to fill in a small cavity in the centre of a knot (bit wary on filling something that has been oiled).

My issue is that I know it was finished with Watco Tung Oil - an American brand. This oil doesn't seem to be available in Australia. I know that not all tung oils are created equal I was just wondering if anyone has any advice/thoughts/recommendations on the risks of applying different brands of tung oil over each other.

Cheers,
Mike

I assume that if you use a 100% pure tung oil, you won't have an issue regardless of what brand was originally used.