Throw it out.
$8.50 is nothing compared to the $ and hours you have already spent.
Oil finishes do not "dry" like water colors, by evaporation of some solvent.
Oil finishes thicken and harden by oxidation, a chemical reaction with the air, enhanced perhaps by sunlight.
"Thinning" with spirits of whatever does not reverse that.
You will have, at best, a weaker film.
Get thee a new bottle of your favorite oil.
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