2018 Kenworth T680 Transmission Fluid & Service

Quick Answer

• Transmission Make/Model: Most commonly Eaton Fuller Advantage Automated Manual Transmissions (AMT) like the Fuller Advantage FO-16E318B-MXP or similar models in the Advantage series.
• OEM Fluid Spec: Eaton PS-386 (Eaton RoadRanger PS-386)
• Drain & Fill Capacity: Varies by model, typically 12-16 quarts (11.4-15.1 liters) for most Advantage AMTs. Always check dipstick.
• Full Overhaul Capacity: Varies by model, typically 16-22 quarts (15.1-20.8 liters). Verify with service manual.
• Filter OEM Part Number: Verify with Eaton dealer or service manual, as filter configurations can vary. Common filters might include an internal suction screen that is cleaned rather than replaced.
• Recommended Service Interval:
  • Normal Duty: Up to 500,000 miles (800,000 km) or 5 years, whichever comes first.
  • Severe Duty/Towing: 250,000 miles (400,000 km) or 2 years, whichever comes first, or more frequently based on fluid analysis.

Fluid Type Explained

The 2018 Kenworth T680, when equipped with an Eaton Fuller Advantage Automated Manual Transmission (AMT), requires a very specific lubricant: Eaton RoadRanger PS-386. This is a proprietary synthetic transmission fluid designed to maximize the efficiency and longevity of Eaton's AMTs.

Unlike traditional automatic transmissions that use ATF (Automatic Transmission Fluid) or manual transmissions that might use gear oil, the Eaton PS-386 is formulated for the unique demands of an AMT. These transmissions combine aspects of both manual and automatic designs, requiring a fluid that can handle high torque, provide excellent thermal stability, and facilitate smooth shifting without compromising clutch life or gear wear. Using any other fluid, such as a standard heavy-duty gear oil or an ATF not approved by Eaton, can lead to premature wear, poor shifting performance, increased fuel consumption, and potential transmission failure. Always ensure that the fluid used explicitly states compliance with or approval for the Eaton PS-386 specification.

Service Procedure: Drain & Fill vs. Full Exchange

For most Eaton Fuller Advantage AMTs in the 2018 Kenworth T680, a drain and fill is the standard and recommended service procedure for routine maintenance.

Drain & Fill Procedure:

1. Preparation: Safely park the truck on a level surface, engage the parking brake, and allow the transmission to cool. Locate the drain plug typically on the bottom of the transmission housing.
2. Draining: Place a suitable drain pan underneath. Remove the drain plug and allow the existing transmission fluid to drain completely. Inspect the drained fluid for any metal particles or unusual discoloration, which could indicate internal wear.
3. Filter (if applicable): While many Eaton AMTs utilize an internal suction screen that is typically cleaned rather than replaced during a standard service, verify your specific model