Kerosene, sold as heater fuel for $1 to $2 per gallon, makes a good substitute for paint thinner, which costs considerably more. Used as a solvent for brushes, kerosene leaves a slight residue on the bristles which helps to keep them supple during storage. This residue can be removed with mineral spirits if necessary. Kerosene will significantly extend the drying time of oil paints, so keep this in mind if you are using it as a thinning agent.
Albert Treadwell, Ridgefield, CT