2024 Peterbilt 579 Eaton Endurant Transmission Fluid & Service

Quick Answer

• Transmission Make/Model: Eaton Endurant Automated Manual Transmission (AMT)
• OEM Fluid Spec: Eaton PS-386 AMSOIL Synthetic Endurant Transmission Fluid (or equivalent meeting Eaton PS-386 specification)
• Drain & Fill Capacity: Approximately 35-39 US Quarts (refer to owner's manual for exact capacity)
• Full Overhaul Capacity: Approximately 39-41 US Quarts (refer to owner's manual for exact capacity)
• Filter OEM Part Number: Verify with Eaton or Peterbilt dealer as the Endurant is filterless externally, relying on internal filtration. Certain models may have an in-line cooler filter.
• Recommended Service Interval:
  • Normal Duty: 500,000 miles or 5 years, whichever comes first.
  • Severe Duty / Vocational / Heavy Haul: 250,000 miles or 2.5 years, whichever comes first.

Fluid Type Explained

The 2024 Peterbilt 579, when equipped with the Eaton Endurant Automated Manual Transmission (AMT), requires a very specific lubricant engineered for optimal performance and longevity. The OEM fluid specification is Eaton PS-386. This is a high-performance synthetic transmission fluid designed to meet the rigorous demands of heavy-duty truck transmissions, particularly AMTs.

Eaton PS-386 fluid provides superior thermal stability, excellent shear stability, and enhanced wear protection for gears and bearings. It also offers improved fuel efficiency due to its optimized viscosity and reduced internal friction. Using any fluid that does not meet the PS-386 specification can lead to premature wear, shifting issues, reduced fuel economy, and potential transmission failure, voiding the warranty.

While AMSOIL often carries a highly-regarded Eaton PS-386 fluid, always ensure that any aftermarket fluid explicitly states compliance with the Eaton PS-386 specification. It's always safest to use the OEM-recommended fluid or an equivalent verified by Eaton.

Service Procedure

Servicing the Eaton Endurant transmission typically involves either a drain and fill or a full exchange.

Drain & Fill:

This is the most common service procedure and involves draining the existing fluid from the transmission pan and refilling it with new fluid. For the Eaton Endurant, this process will replace the majority of the fluid, but a small amount will remain in the torque converter (if equipped) and cooler lines. The drain and fill capacity for the Eaton Endurant is approximately 35-39 US Quarts. Always consult your Peterbilt 579 owner's manual or a service manual for the exact capacity specific to your truck's configuration.

Full Exchange:

A full fluid exchange, sometimes referred to as a fluid flush, involves using specialized equipment to completely remove all old fluid from the transmission, including what’s in the cooler and lines, and then replenishing it with new fluid. This method ensures nearly 100% new fluid. A full overhaul capacity for the Eaton Endurant is approximately 39-41 US Quarts. While a full exchange can be beneficial, it