The right refill fluid for Ritchie compassesIf you ever need to refill or top off the fluid in your Ritchie compass, the manufacturer recommends Isopar L, an odorless, colorless, refined synthetic fluid. Its low viscosity promotes quick swinging. Won't freeze or boil off at temperatures from -40 to 200 F., and it may be mixed with the mineral oil already in compasses made before 2001. Sold by the pint or the quart