The purpose of the differential gears that are present in on-road drive axles is to permit each wheel to turn at a different speed than the other to prevent “wheel skip” when the vehicle is turning. Unfortunately, this causes conventional rear-wheel-drive axles to have a disadvantage when one wheel is on a slippery surface. All of the torque gets transferred to this wheel resulting in wheel spin, while the other wheel and the vehicle do not move.
One of the more common ways to remedy this issue is to build the axle with a clutch mechanism which senses when one wheel has reduced torque from being on a slippery surface and routes torque to the wheel with good traction. This clutch mechanism requires a gear oil having a lower coefficient of friction than the typical GL-5 gear oil to achieve proper and noise (chatter)-free operation.
A limited slip gear oil contains a friction modifier component in addition to gear oil EP components and possesses the required frictional properties. Limited slip gear oils can be used in both limited slip and non-limited slip axles.
Castrol’s limited slip automotive GL-5 gear oil products include the mineral oil-based Castrol Axle Limited Slip 80W-90, the part-synthetic Castrol Axle Limited Slip 75W-90 and the full-synthetic Castrol Syntrax Limited Slip 75W-90.
These products offer Castrol customers a range that is capable of servicing most vehicles requiring a limited slip GL-5 gear oil.