Gary,50/50 mixture of linseed oil and turpentine?
"Because kerosene was first derived from cannel coal, classified as terrestrial type of oil shale,[2] it continued to be popularly referred to as "coal oil" even after production shifted to petroleum as a feedstock.[3][4][5] Refined hydrocarbons of the alkane series with 10 to 16 carbon atoms are the same thing whether taken from coal or petroleum."
Your experience may be limited but I have seen your work and you should give yourself, more credit. I do restoration work and replace broken rods on a regular basis. Mostly good old American Hickory but have done some exotic woods like Ebony and Rosewood. I buy my Hickory stock in lots of 100 and hand select the straightest for the longer rods. I coat my rods with Watco Deep Penetrating oils, three to four passes. ....In my limited experience of about 55 years of shooting building and repairing ram rods. Seems to me selection of grain run out and how you use it has the greatest effect.
For hunting use, I make a Delrin rods and don't worry about soaking the wooden rods. For range use, I retain the wooden rod and use a Poly range-rod. Some folks have learned, the hard way about using fibreglass rods. .......(and to use a synthetic rod in the field).