I just don't get it. Why do you have to do anything other than a bit of wax? Now, I have to admit that there is a time and place for Tung oil, true oil or whatever but what are we really trying to fix. I am a woodcrafter and have never used mineral oil nor understand it's properites over just plain Linseed oil. I have used a mixture of Linseen oil, Spar varnish and Turpentine equal parts and use that not so much as a refinish but as a light protective coating. Be very conservative in the checkering. Perhaps look the grips over before you decide what is needed
Be Safe !!!