![The Difference Between GL-4 and GL-5 Gear Lube The Difference Between GL-4 and GL-5 Gear Lube](https://syntheticwarehouse.com/wp-content/uploads/2023/03/SevereGear-Ford-pick-up-306x205.jpg)
The Difference Between GL-4 and GL-5 Gear Oil The main difference between GL-4 and GL-5 gear oils is in the level of extreme-pressure (EP) additives. It’s really very simple. They are not interchangeable and GL5 didn’t replace GL4. by Eddie…
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