GL-4 is suitable for hypoid gear service when they are under severe service but are without shock loading. GL-5 is suitable for hypoid gear service under severe service and shock loads and not for use in a gearbox.

Can I use GL4 instead of GL5?

No, you shouldn’t use GL-4 if GL-5 is called for. GL-5 is the classification for extreme pressure rating. GL-4 oil of any viscosity has about the sulfur and other additives of GL- 5.

Does it matter what gearbox oil I use?

Lower and higher viscosity oils are suited to different applications. Lower-viscosity gear oils offer better protection and lubrication for high-speed gearboxes that are under relatively low loads thanks to their improved cooling abilities and thinner films which better coat fast-moving components.

What is GL5 transmission fluid?

HP Gear Oil GL-5 is high performance gear oil with advanced extreme pressure additive for maximum protection on gear teeth suitable for gear box and final drive for all types of automobiles and can be applied for industrial gearbox.