The tar like crap is probably cosmoline, used for preserving steel parts,tools, and other steel items, usually applied right after manufacture, so it has a good chance of being in excellent condition. Kerosene or any Stoddard solvent will remove the cosmoline, but it may take a little scrubbing with a rag. Don't use a scotch brite pad as it will scratch any plating that has been applied to the wrench. Also, never use any gasoline to clean anything as it is very dangerous and can also damage the finish. Plus there are better cleaners out there anyway. Good luck.