Mack Pinnacle series (CHU/CXU)

Differential fluid capacity & service interval

Mack Pinnacle series (CHU/CXU) differential fluid capacity ranges from 16.1 to 17 liters. Service intervals include 40000 miles/12 months/1200 hours, 80000 miles/12 months/1200 hours, 250000 miles/24 months, and 500000 miles/36 months. The data covers 12 configurations.

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

TypeSpecifications
  • Pinnacle P7 GHG22 (2021- )
  • Rear
  • Use: Vocational
  • Capacity 16,1-17 liter
  • Change 40000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle P7 GHG22 (2021- )
  • Rear
  • Use: Vocational, extended
  • Capacity 16,1-17 liter
  • Change 80000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle P7 GHG22 (2021- )
  • Rear
  • Use: Highway use
  • Capacity 16,1-17 liter
  • Change 250000 miles/ 24 months
  • Code: Mack
  • Pinnacle P7 GHG22 (2021- )
  • Rear
  • Use: Highway use, extended
  • Capacity 16,1-17 liter
  • Change 500000 miles/ 36 months
  • Code: Mack
  • Pinnacle MP7 GHG17, GHG21 (2016-2021)
  • Rear
  • Use: Vocational
  • Capacity 16,1-17 liter
  • Change 40000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle MP7 GHG17, GHG21 (2016-2021)
  • Rear
  • Use: Vocational, extended
  • Capacity 16,1-17 liter
  • Change 80000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle MP7 GHG17, GHG21 (2016-2021)
  • Rear
  • Use: Highway use
  • Capacity 16,1-17 liter
  • Change 250000 miles/ 24 months
  • Code: Mack
  • Pinnacle MP7 GHG17, GHG21 (2016-2021)
  • Rear
  • Use: Highway use, extended
  • Capacity 16,1-17 liter
  • Change 500000 miles/ 36 months
  • Code: Mack
  • Pinnacle MP8 GHG17, GHG 21 (2016-2021)
  • Rear
  • Use: Vocational
  • Capacity 16,1-17 liter
  • Change 40000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle MP8 GHG17, GHG 21 (2016-2021)
  • Rear
  • Use: Vocational, extended
  • Capacity 16,1-17 liter
  • Change 80000 miles/ 12 months/ 1200 hours
  • Code: Mack
  • Pinnacle MP8 GHG17, GHG 21 (2016-2021)
  • Rear
  • Use: Highway use
  • Capacity 16,1-17 liter
  • Change 250000 miles/ 24 months
  • Code: Mack
  • Pinnacle MP8 GHG17, GHG 21 (2016-2021)
  • Rear
  • Use: Highway use, extended
  • Capacity 16,1-17 liter
  • Change 500000 miles/ 36 months
  • Code: Mack

Additional Notes

  • The Mack Pinnacle series (CHU/CXU) rear differential fluid capacity is listed as a range of 16.1 to 17 liters across all configurations covered in the 2016-2021 model years, reflecting the fill tolerance typical of axle housings where exact volume depends on the angle and method of fill rather than a fixed measured quantity.
  • Under vocational use conditions, the rear differential fluid change interval is set at 40,000 miles, 12 months, or 1,200 hours, whichever comes first, for both the MP7 and MP8 engine variants in the 2016-2021 range.
  • A vocational extended interval doubles the mileage threshold to 80,000 miles while retaining the same 12-month and 1,200-hour limits, meaning the time and hour caps remain binding regardless of the mileage extension.
  • Highway use conditions carry a substantially longer change interval of 250,000 miles or 24 months, a figure that reflects the lower thermal and contamination stress placed on differential fluid during sustained, consistent-speed road operation compared to stop-and-go or off-road vocational cycles.
  • The highway use extended interval reaches 500,000 miles or 36 months, which represents the longest service interval in the specifications and applies equally to the MP7 and MP8 engine configurations across the 2016-2021 model years.
  • The MP7 and MP8 engine variants share identical rear differential fluid capacities and change intervals across all four use conditions, indicating no differentiation in axle service requirements between the two powertrains for the 2016-2021 Pinnacle series.
  • The P7 GHG22 engine variant, introduced with a starting year of 2021, carries the same 16.1 to 17 liter rear differential capacity and the same four-tier interval structure as the earlier GHG17 and GHG21 configurations.
  • Across all engine variants and use conditions in the specifications, the rear differential capacity range of 16.1 to 17 liters remains constant, suggesting a consistent axle assembly is used throughout the Pinnacle series configurations covered here.

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