patrick_g
Elite Member
My '64 Ford 1/2 ton was converted to propane only (Stelite valves and seats) and was rated for 100,000 miles on spark plugs (a loooong time for that vintage.) The instructions for fleet operators was to change the filter and top off the oil. Oil analysis was recommended and you needed to use lighter viscosity oil for the top off (as indicated by analysis) because the lighter fractions evaporated away faster changing the viscosity of the oil.
Pat
Pat