2020 International MV Transmission Fluid, Capacity & Service Guide

As an ASE-certified master technician, I regularly work on medium-duty trucks that serve as the backbone of local delivery, construction, and municipal fleets. The 2020 International MV is a prime example of a versatile, hard-working truck. Depending on the exact spec of your MV, it is most commonly equipped with an Allison automatic transmission—typically the Allison 2000 Series (like the 2500 RDS) or the heavier-duty Allison 3000 Series (like the 3000 RDS). Less commonly, they can be found with Eaton Fuller automated manual or manual transmissions.

For the purposes of this guide, we will focus on the most popular configurations: the Allison 2000 and 3000 Series automatics. Keeping the transmission fluid clean and maintained is the single most important factor in ensuring these heavy-duty gearboxes survive thousands of hours of punishing operation.

Here is your comprehensive transmission fluid, capacity, and service guide for the 2020 International MV.

Quick answer: 2020 International MV Transmission Specs

• Transmission Make/Model: Allison 2000 Series (e.g., 2500 RDS) or Allison 3000 Series (e.g., 3000 RDS)
• OEM Fluid Spec: Allison TES 668™ (fully backward compatible with and superseding TES 295®)
• Drain & Fill Capacity:
  • Allison 2000 Series: Standard pan approx. 10.6 quarts (10 liters).
  • Allison 3000 Series: 4-inch sump approx. 19 quarts (18 liters); 2-inch sump approx. 16 quarts (15 liters).
• Full Overhaul Capacity:
  • Allison 2000 Series: Approx. 15 quarts (14 liters).
  • Allison 3000 Series: 4-inch sump approx. 29 quarts (27 liters).
• Filter OEM Part Number:
  • Allison 3000 Series: Often utilizes the High-Capacity Filter Kit (verify with dealer or service manual based on sump depth; common kit part number 29558118 for 4-inch sumps).
  • Allison 2000 Series: Uses a spin-on external filter (e.g., 29539579) and an internal suction filter. Always verify exact part numbers with your International or Allison dealer using your truck's VIN.
• Recommended Service Interval: Up to 300,000 miles or 48 months for general duty using TES 668/295 fluid and Allison High-Capacity filters. Severe duty/PTO operations require shorter intervals.

Fluid type explained

For the 2020 International MV with an Allison automatic, the gold standard for transmission fluid is an Allison TES 668™ approved fluid. Introduced in 2021 as the next-generation synthetic fluid, TES 668 is fully backward compatible with the legendary TES 295® specification that your truck originally called for when it rolled off the assembly line.

Why use TES 668 instead of cheaper alternatives? Medium-duty trucks generate a massive amount of heat and torque shear. TES 668 fluids are engineered to improve shift quality, reduce noise and vibration, and dramatically extend fluid and filter life. If you use a non-approved fluid (like a standard DEXRON®-III or generic heavy-duty ATF), you cut your service intervals by up to 50% and risk premature clutch wear and valve body degradation. Always look for the Allison Approved TES 668 logo on the bottle or drum.

Service procedure

When servicing an Allison transmission in an International MV, a drain and fill is the standard, manufacturer-approved method. Full flush machines that use harsh chemicals or back-pressure are generally discouraged by Allison, as they can dislodge debris into the valve body or damage internal seals.

Drain and Fill Process:

1. Warm up the fluid: Drive the truck to reach normal operating temperature (usually 160°F - 200°F).
2. Drain the pan: Remove the drain plug and allow the fluid to drain completely.
3. Replace the filters:
   • For the 3000 Series, remove the covers for the main and lube filters located on the bottom of the transmission. Swap the cartridge filters, replace the O-rings, and torque the cover bolts to factory specifications.
   • For the 2000 Series, replace the external spin-on control main filter. Transfer the reusable magnet from the old spin-on filter to the new one! The internal filter usually only needs replacement during an overhaul.
4. Refill and Check: Refill with the appropriate amount of TES 668 fluid. Start the engine, shift through all gears while stationary, and check the fluid level using the dipstick or the push-button shift selector's oil life monitor/level check function (if equipped). Do not overfill, as this causes aeration and overheating.

Service interval

The beauty of Allison's TES 668 and TES 295 fluids paired with high-capacity filters is the extended service intervals. However, your exact interval depends heavily on how you use your International MV.

• Normal Duty (Highway / General Cargo): Under normal operating conditions, fluid and filters can often go up to 300,000 miles, 4,000 hours, or 48 months (whichever comes first).
• Severe Duty (Refuse, Dump, Towing, Heavy PTO usage): If your MV is used in stop-and-go refuse collection, heavy towing, or utilizes a PTO (Power Take-Off) extensively, the intervals drop significantly. Fluid and filter changes are typically recommended every 150,000 miles, 3,000 hours, or 24 months.
• Note: Always utilize fluid analysis (oil sampling) to maximize the life of your fluid while protecting your investment.

Common transmission problems

The Allison 2000 and 3000 Series transmissions in the 2020 International MV are renowned for their bulletproof reliability, but they are not immune to issues, particularly if neglected:

1. Shift Flare or Harsh Shifting: Often caused by degraded fluid, low fluid levels, or someone skipping the filter change. If a non-approved fluid was used, the clutch packs can glaze, causing harsh engagements.
2. TCM Communication Faults: The Transmission Control Module (TCM) relies on clean electrical connections. Wiring harness rub-throughs along the frame rails or water intrusion in the connectors can cause the transmission to go into "Limp Mode" (locking into a single gear).
3. PTO Engagement Issues: On trucks equipped with a PTO, failing to maintain fluid levels or using degraded fluid can cause the PTO gear to engage harshly or fail to engage at all due to pressure drops.
4. Cooler Line Leaks: The transmission cooler lines running from the transmission to the radiator/heat exchanger are prone to vibration wear and corrosion. Inspect them regularly for weeping fluid.

Proper maintenance is the key to keeping this commercial workhorse on the road and out of the shop.

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