Which type of differential requires a special lubricant additive?

The type of differential that requires a special lubricant additive is the limited-slip differential. These differentials are designed to allow some differences in wheel speed between the left and right wheels while still providing some level of bias to the wheel with better traction. They often utilize a friction mechanism to achieve this, which can create higher temperatures and necessitate the use of a specialized lubricant to help reduce friction and prevent wear.

Regular gear oil may not be sufficient for a limited-slip differential as it could lead to the clutches in the differential prematurely wearing out. The special additive in the lubricant helps to ensure proper operation and longevity of the differential components by providing the necessary friction characteristics.

Other types of differentials, such as open differentials and locking differentials, typically do not require such specialized lubricants, as they operate on different principles. An open differential allows for full speed differences between the two wheels without accounting for traction differences, while a locking differential can fully engage both wheels to rotate at the same speed when needed. A Torsen differential, which uses a worm gear system for torque distribution, also operates effectively with regular gear oils without the need for additional additives.