Industrial Lubricants - Viscosities vs. ISO-VG Grade
Lubrication Selection for Enclosed Gear Drives
Calculators and Formulas - Oil Viscosity Chart
Effect of gear oil viscosity on transmission efficiency (Metro owners take note) - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com
How thick gear oil with SAE 250W is? | Bob Is The Oil Guy