Caterpillar Off highway tractors

Differential fluid capacity & service interval

Caterpillar Off highway tractors require differential fluid with a capacity range of 222 to 379 liters. Service intervals include checking every 3 months or 500 hours and changing every 12 months or 2000 to 4000 hours. The data covers 7 configurations.

The configuration chart below lists fill volumes and service intervals for each engine and trim variant.

TypeSpecifications
  • 777G, RDR (2012- )
  • Rear
  • Use: Normal
  • Capacity 227 liter
  • Capacity 379 liter (+ hub reductions)
  • Check 3 months/ 500 hours
  • Change 12 months/ 4000 hours
  • 777G, T4Y (2012- )
  • Rear
  • Use: Normal
  • Capacity 227 liter
  • Capacity 379 liter (+ hub reductions)
  • Check 3 months/ 500 hours
  • Change 12 months/ 4000 hours
  • 777G, T5A (2012- )
  • Rear
  • Use: Normal
  • Capacity 227 liter
  • Capacity 379 liter (+ hub reductions)
  • Check 3 months/ 500 hours
  • Change 12 months/ 4000 hours
  • 777G, TNM (2012- )
  • Rear
  • Use: Normal
  • Capacity 227 liter
  • Capacity 379 liter (+ hub reductions)
  • Check 3 months/ 500 hours
  • Change 12 months/ 4000 hours
  • 777F, JXP (2007- )
  • Rear
  • Use: Normal
  • Capacity 222 liter
  • Check 3 months/ 500 hours
  • Change 12 months/ 4000 hours
  • 776D
  • Rear
  • Use: Normal
  • Capacity 222 liter
  • Check 3 months/ 500 hours
  • Change 12 months/ 2000 hours
  • 776D
  • Rear
  • Use: Preferred
  • Capacity 222 liter
  • Check 3 months/ 500 hours
  • Change 12 months/ 2000 hours

Additional Notes

  • The Caterpillar 776D rear differential holds 222 liters, a figure that applies equally under both normal and preferred fluid designations, indicating the capacity is fixed regardless of fluid type selection.
  • The 777F (JXP serial prefix, from 2007) shares the same 222-liter rear differential capacity as the 776D, placing both models in the same fill volume class despite being distinct machine configurations.
  • The 777G variants across all four serial prefixes (RDR, T4Y, T5A, TNM, all from 2012) carry a base rear differential capacity of 227 liters, a modest increase over the 776D and 777F figures.
  • When hub reductions are present on 777G models, the total differential fluid capacity rises substantially to 379 liters, reflecting the additional volume required to service the planetary hub reduction assemblies integrated into the rear axle system.
  • The 152-liter difference between the standard 227-liter and the hub-reduction 379-liter fill on 777G models represents the fluid volume held within the hub reduction housings themselves, which are filled and serviced as part of the same differential system.
  • The 776D check interval of every 3 months or 500 hours applies under both normal and preferred use conditions, with a change interval set at 12 months or 2,000 hours under either designation.
  • The 777F and all 777G serial prefix variants share a check interval of 3 months or 500 hours, but carry a change interval of 12 months or 4,000 hours, doubling the hour-based drain interval compared to the 776D.
  • The extended 4,000-hour change interval on the 777F and 777G models, versus the 2,000-hour interval on the 776D, reflects a meaningful difference in fluid longevity expectations between the two machine generations under normal operating conditions.

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