2024 International LT Fluid Capacity and Specifications

As an ASE-certified master technician, I know that using the correct fluid is critical to the longevity and reliability of any vehicle, especially a heavy-duty truck like the 2024 International LT. These are not just "recommendations"; they are precise engineering requirements. Using the wrong fluid can lead to premature wear, component failure, and costly downtime.

This guide provides a comprehensive list of the factory-specified fluids for the 2024 International LT series. Always verify these specifications against your owner's manual or OEM service information, as capacities and exact specs can vary based on the specific engine, transmission, and axle options your truck is equipped with.

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	API CK-4; SAE 15W-40, 10W-30	42 - 44 quarts (approx.)
Engine Coolant	OAT ELC; Nitrite-Free, Extended Life	14 - 16 gallons (approx.)
Transmission Fluid	Varies by transmission model	Varies
Rear Differential	SAE 75W-90 / 80W-140 Synthetic Gear Lubricant	16 - 34 pints (approx.)
Brake Fluid	DOT 3 / DOT 4	As required
Power Steering	N/A (Electric Power Steering)	N/A
Windshield Washer Fluid	All-Season / Bug Remover	2.5 gallons
Diesel Exhaust Fluid (DEF)	API Certified / ISO 22241	10 - 20 gallons

Engine Oil

The lifeblood of your Cummins X15 or International S13 engine is its oil. For the 2024 International LT, you must use an oil that meets the API Service Category CK-4. This specification was designed for modern, high-speed, four-stroke diesel engines to protect against oil oxidation, viscosity loss from shearing, and catalyst poisoning.

• Specification: API CK-4
• Viscosity: The most commonly recommended viscosity grades are SAE 15W-40 for all-around performance and SAE 10W-30 for improved fuel economy and cold-weather starting. The choice depends on your climate and operational demands. Using a high-quality synthetic blend or full synthetic CK-4 oil can provide superior protection, especially under severe service conditions.
• Capacity: Approximately 42-44 quarts, but always confirm by checking the dipstick after filling.
• Note: Never use older API categories like CJ-4 or CI-4 unless explicitly permitted for a specific engine, as they may not provide adequate protection for the advanced emissions systems on 2024 models.

Engine Coolant

Modern diesel engines run hot and require a specific coolant formulation to prevent corrosion and ensure proper heat transfer. The 2024 International LT uses a Nitrite-Free Organic Additive Technology (OAT) Extended Life Coolant (ELC).

• Specification: Nitrite-Free OAT ELC. Look for coolants that meet Cummins CES 14603 or similar OEM specifications.
• Type: This is typically a red or pink-colored coolant. Crucial Pitfall: Never mix OAT coolants with older Inorganic Additive Technology (IAT - green) or Hybrid Organic Additive Technology (HOAT) coolants. Mixing chemistries can cause the coolant to gel, leading to blockages, overheating, and catastrophic engine damage.
• Capacity: Roughly 14-16 gallons for the system. Always use a 50/50 mix of concentrated coolant and deionized or distilled water.

Transmission Fluid

The correct fluid for your transmission is entirely dependent on which unit is installed in your LT. Eaton-Fuller, Allison, and other manufacturers have unique requirements.

• Specification: This is not a one-size-fits-all situation. You must identify your transmission model to determine the correct fluid.
  • For Eaton automated manuals (Endurant series), use a fluid meeting Eaton PS-386 specification.
  • For Allison automatics, use a TES 668 approved fluid (the successor to TES 295).
• Note: Using a "universal" or incorrect type of ATF can destroy a transmission in short order. There is no substitute for using the OEM-specified fluid. Check the data plate on the transmission housing for identification.

Rear Differential Fluid

Axle lubrication is essential for preventing wear on the ring and pinion gears. The 2024 LT requires a high-quality synthetic gear lubricant.

• Specification: SAE 75W-90 or SAE 80W-140 synthetic gear lubricant. The heavier 80W-140 is often specified for heavy-haul applications or extreme temperature environments.
• Capacity: Varies significantly based on the axle model, typically from 16 to 34 pints. Check the manufacturer (e.g., Meritor, Dana) specifications for your specific axle.
• Note: If your truck is equipped with a limited-slip or locking differential, ensure the gear oil is compatible or that the required friction modifier additive is included.

Brake Fluid

The air brake system on the LT does not use "brake fluid" in the traditional sense of a hydraulic fluid that needs regular changing. The system operates on compressed air. However, various hydraulic clutch and other small systems may use standard brake fluid.

• Specification: If a hydraulic system calls for it, use DOT 3 or DOT 4 brake fluid from a sealed container.

Power Steering Fluid

The 2024 International LT is equipped with an Electric Power Steering (EPS) system. This system uses an electric motor to provide steering assist, eliminating the need for a hydraulic pump, hoses, and power steering fluid. There is no fluid to check or change.

Windshield Washer Fluid

While seemingly minor, clear visibility is a major safety factor. Keep the reservoir full.

• Specification: Any high-quality, all-season windshield washer fluid will suffice. In winter, use a fluid with an appropriate freeze protection rating. In summer, a "bug remover" formula can be effective.
• Capacity: Approximately 2.5 gallons (10 liters).

Diesel Exhaust Fluid (DEF)

DEF is critical for the operation of the Selective Catalytic Reduction (SCR) system, which reduces NOx emissions.

• Specification: Use only DEF that is API Certified and meets the ISO 22241 standard. This ensures the proper purity and urea concentration (32.5%).
• Note: Using non-compliant fluid can damage the expensive SCR system. Never put anything other than fresh, pure DEF into the DEF tank. The tank is identified by a blue cap.
• Capacity: DEF tanks typically hold between 10 and 20 gallons.

Using the correct, high-quality fluids is one of the most important investments you can make in your 2024 International LT. It ensures reliability, protects your warranty, and keeps your truck on the road making money.

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