The Isopar L is just one of a family with its boiling point of 189 deg C. Isopar C has a BP of 100 deg C. Isopar V has a BP of 272 deg C. The boiling point is an indication of molecular length and therefore its viscosity. Kingsford charcoal starter lists its BP as 174 deg C.

Also important to note is the odorless nature. Odorless mineral spirits are highly treated with mole sieves to remove of aromatics and unsaturated molecules which lead to order and chemical re-activeness. Painting mineral spirits in not well refined. I would prefer to have the odorless fluid of proper viscosity in the compass. Jerry Goedken, Retired chemist, Frequent viewer, infrequent poster.:)