WM,
First, credit where credit is due-- scottg turned me on to the Galloot Mixture/Method. I have simply adapted it to my particular projects.
My wood handle was in pretty good shape, just scratched/nicked up, dirty, and oil soaked. No splits or cracks and the rivets were still holding firm.
1) Soaked it in clean paint thinner and scrubbed it with tooth brush to get all the old motor oil and dirt out of the wood. Then let it air dry.
2) Sanded the handle smooth with 220 grit dry paper followed by 0000 steel wool.
3) Dipped the handle in hot Galoot Mixture (1 part paint thinner/1 part paraffin/1 part boiled linseed oil, heated and mixed) and left to soak for an hour. Removed from Gallot mix, wiped with paper towel and buffed with 0000 steel wool.
4) Repeated step 3 two more times.
5) Done. But note, step 3 can be reapplied at any point in the future as the the handle ages, wears, or gets dirty.
Warning-- When mixing or heating the Galoot mixture, do not do this on a stove, as the mixture is flamable. I have found that the ingredients can safely be heated in a microwave oven. Just place the ingredients in a microwave safe plastic container and use the high setting for 30-120 seconds; just long enough to melt the paraffin.
Good luck and have fun with it...