1981 4cyl Landrover engine is as close to a 1950s tractor engine that you can get without actually being one.
Density at 15°C, kg/L 0.881
Viscosity, Kinematic, cSt at 40°C 325
Viscosity, Kinematic, cSt at 100°C 31.2
Viscosity Index 133
Cold Cranking Viscosity, cP at -10°C 8166
Ca content, Mass...