I think it is humorous, as every now & then I hear someone say "Well back in the ol days" or "My great great great grandaddy", them not knowing that coal oil or kerosene was not even around then....... Turner Kirkland started that baloney back in the 60's I guess. IMHO, you end up with a RR a mouse won't eat & it stinks & it sweats kerosene when out in the sun & it won't stain. I soaked some 35 years ago, as I just had to try it, it was the new thing....... all I succeeded in doing was making 6 RR's smell bad.
That being said, it is a cheap experiment if ya want to do it. 48" piece of 1.5" PVC pipe, glue cap on one end, glue union on other end, put in RR's, fill with lamp oil or Kerosene, screw in cap & stand in the corner. Soak them for however long you want, take one out & check it, guaranteed they will always smell like kerosene.
Keith Lisle