Hypoid gears load their teeth in sliding contact, not just rolling, which is why axle lubricant needs an extreme pressure additive package rather than plain oil. The MS-8985 standard identifies the formulation the differential was engineered around, and a synthetic base holds viscosity better across the temperature swing between a cold start and a loaded highway pull.

Fluid Specifications:

• SAE 75W-90 synthetic axle lubricant.
• Meets Chrysler Material Standard MS-8985.
• For select Chrysler, Dodge, Jeep and Ram axle applications.
• 32 oz. bottle.
• Confirm whether your axle also requires a limited slip additive.