Gear and differential oil keeps the gears and bearings in your transmission and axles running smoothly under heavy load. Unlike engine oil, which circulates through the engine block, gear oil stays in the transmission housing or differential case where it protects components that mesh together at high pressure. The right gear oil prevents wear, reduces heat buildup, and keeps metal-to-metal contact from causing damage or noise.
These articles cover what separates one gear oil from another—viscosity grades, additives that handle extreme pressure, and how synthetic versus conventional formulations perform in different conditions. You'll find information about matching the correct oil to your vehicle's transmission type, recognizing when gear oil needs changing, and understanding why some differentials require special limited-slip additives.