2025 International MV Transmission Fluid & Service Spec

Quick Answer

• Transmission Make/Model: Allison 3000 Series (common in MV models)
• OEM Fluid Spec: Allison TES 668
• Drain & Fill Capacity: Approximately 19 quarts (varies by pan depth and cooler size)
• Full Overhaul Capacity: Approximately 29 quarts (varies by pan depth and cooler size)
• Filter OEM Part Number: Verify with International dealer or Allison service manual as part numbers can vary based on pan type and year.
• Recommended Service Interval:
  • Normal Duty: 4 years or 100,000 miles
  • Severe Duty/Towing: 2 years or 50,000 miles

Fluid Type Explained

The 2025 International MV series, when equipped with the popular Allison 3000 Series automatic transmission, utilizes a highly specialized heavy-duty transmission fluid. The OEM specification is Allison TES 668. This is a crucial detail, as using the incorrect fluid can lead to premature wear, performance issues, and even catastrophic transmission failure.

Allison TES 668 is an advanced synthetic fluid designed to provide superior performance and protection in demanding commercial vehicle applications. Its key benefits include:

• Extended Drain Intervals: TES 668 allows for longer service intervals compared to older specifications, reducing maintenance costs and downtime.
• Enhanced Thermal Stability: It maintains its protective properties under high operating temperatures, preventing fluid breakdown and oxidation.
• Improved Shear Stability: The fluid resists thinning under extreme stress, ensuring consistent film strength for optimal gear and bearing protection.
• Better Cold Weather Performance: Offers improved flow characteristics in cold temperatures, aiding in quicker starts and reduced wear during warm-up.
• Optimized Friction Characteristics: Ensures smooth and consistent shifting, reducing clutch wear and improving overall transmission efficiency.

Always ensure that any fluid used explicitly states compliance with Allison TES 668. Do not substitute with earlier Allison specifications (like TES 295) unless specifically approved by Allison Transmission for your exact model and duty cycle.

Service Procedure

Servicing the transmission fluid in a 2025 International MV typically involves one of two methods: a drain and fill, or a full fluid exchange (flush).

Drain & Fill:

This method involves draining the fluid from the transmission pan and replacing the filter(s), then refilling with new fluid. This is the most common DIY or basic service procedure. While it replaces a significant portion of the fluid, it does not remove all the old fluid from the torque converter, cooler lines, and cooler. For the Allison 3000 Series, a drain and fill typically replaces around 19 quarts of fluid.

Full Fluid Exchange (Flush):

A full fluid exchange uses specialized equipment to completely remove all the old fluid from the entire transmission system, including the torque converter and cooler circuit, and replace it with new fluid. This method is recommended for optimal performance and fluid longevity, especially when transitioning to a new fluid type or after prolonged severe duty. A full fluid exchange for the Allison 3000 Series will require approximately 29 quarts, ensuring all components are filled with fresh TES 668 fluid.

Regardless of the method, always:

1. Use the correct Allison TES 668 fluid.
2. Replace both the main filter and the lube filter (if two are present). Verify the correct filter part numbers with your International dealer or Allison service manual, as these can vary.
3. Ensure the transmission is at the correct operating temperature for an accurate fluid level check, following the manufacturer