Peterbilt On highway trucks

Differential fluid capacity & service interval

Peterbilt On highway trucks utilize differential fluid with a capacity range of 9,3 to 11,3 liters. Service intervals include checking at 30000 miles and changing at 60000 miles or 6 months, or 500000 miles or 48 months. The data covers 4 configurations.

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

TypeSpecifications
  • 579 New model, MX-11 (2021- )
  • Rear, tandem
  • Use: On-Highway
  • Capacity 11,3 liter (Forward rear axle)
  • Capacity 9,3 liter (Rear rear axle)
  • Check 30000 miles
  • Change 500000 miles/ 48 months
  • Code: Paccar DX-40
  • 579 New model, MX-11 (2021- )
  • Rear, tandem
  • Use: City usage
  • Capacity 11,3 liter (Forward rear axle)
  • Capacity 9,3 liter (Rear rear axle)
  • Change 60000 miles/ 6 months
  • Code: Paccar DX-40
  • 579 New model, MX-13 (2021- )
  • Rear, tandem
  • Use: On-Highway
  • Capacity 11,3 liter (Forward rear axle)
  • Capacity 9,3 liter (Rear rear axle)
  • Check 30000 miles
  • Change 500000 miles/ 48 months
  • Code: Paccar DX-40
  • 579 New model, MX-13 (2021- )
  • Rear, tandem
  • Use: City usage
  • Capacity 11,3 liter (Forward rear axle)
  • Capacity 9,3 liter (Rear rear axle)
  • Change 60000 miles/ 6 months
  • Code: Paccar DX-40

Additional Notes

  • The Peterbilt 579 with tandem rear differentials carries asymmetric axle capacities: the forward rear axle holds 11.3 liters while the rear rear axle holds 9.3 liters, a difference of 2 liters between the two positions in the tandem setup.
  • Both the MX-11 and MX-13 engine configurations in the 579 New model share identical differential fluid capacities of 11.3 liters for the forward rear axle and 9.3 liters for the rear rear axle, meaning engine displacement does not influence the differential fill volumes.
  • Under on-highway use conditions, the change interval extends to 500,000 miles or 48 months, whichever comes first, reflecting the relatively consistent thermal and load cycles associated with long-haul highway operation.
  • City usage conditions reduce the change interval dramatically to 60,000 miles or 6 months, compared to the 500,000-mile on-highway interval, a reduction that reflects the more frequent stop-and-go cycling and elevated stress placed on differential fluid in urban driving environments.
  • On-highway specifications include a fluid check at 30,000 miles as a separate, intermediate service action, which occurs well before the full change interval and serves as a monitoring step rather than a replacement event.
  • The city usage rows do not list a separate check interval, only a change interval of 60,000 miles or 6 months, in contrast to the on-highway rows which specify both a 30,000-mile check and a 500,000-mile change.

Other Systems