2024 Kenworth T680 Fluid Type Specifications

As an ASE-certified master technician, I've compiled a comprehensive guide to the factory-spec fluids for your 2024 Kenworth T680. Adhering to these specifications is crucial for maintaining optimal performance, longevity, and warranty compliance of your heavy-duty truck.

Quick reference

Fluid	Type/Spec	Capacity
Engine Oil	API CK-4 / FA-4 (dependent on engine)	Varies by engine (e.g., PACCAR MX-13: 42-45 quarts)
Engine Coolant	PACCAR-approved Extended Life Coolant (ELC) - OAT	Varies by system (typically 60-70 quarts)
Transmission Fluid	Eaton PS-386 (manual), Allison TES-295 or TES-668 (auto)	Varies by transmission model
Rear Differential	API GL-5, SAE 75W-90 or 80W-90	Varies by axle model (typically 12-25 quarts per axle)
Power Steering	Allison Original Equipment Power Steering Fluid or equivalent meeting C4 requirements	Varies by system
Brake Fluid	DOT 4 (hydraulic systems, if applicable)	As required
Washer Fluid	Commercial Windshield Washer Solvent	Varies (typically 1-2 gallons)
DEF	ISO 22241 (API DEF)	Varies (typically 15-20 gallons)

Engine Oil

The 2024 Kenworth T680 can be equipped with various engines, most commonly the PACCAR MX-13 or Cummins X15. The specific engine oil requirement will depend on the engine installed in your truck.

• PACCAR MX-13 Engine: Requires API CK-4 or FA-4 engine oil. The choice between CK-4 and FA-4 depends on the specific engine calibration and intended use, with FA-4 offering potential fuel economy benefits in engines designed for it. Always consult your owner's manual or the engine dataplate/decal for the precise viscosity grade (e.g., SAE 10W-30, 5W-30, 5W-40) and API service category.
• Cummins X15 Engine: Typically requires API CK-4 or FA-4 engine oil, again with the specific viscosity grade determined by ambient operating temperatures and engine calibration. Cummins often provides specific material specifications (e.g., CES 20086 for CK-4, CES 20087 for FA-4).

Capacity: Engine oil capacities are significant for heavy-duty engines. For the PACCAR MX-13, capacities can range from 42 to 45 quarts depending on the oil pan design and filters. Always refer to your owner's manual for the exact capacity for your specific engine configuration.

Intervals and Pitfalls: Engine oil change intervals are critical for heavy-duty trucks and are often extended compared to light-duty vehicles. These intervals are typically based on mileage, engine hours, or fuel consumption and can vary significantly based on oil analysis results and operating conditions. Always adhere to the manufacturer's recommended oil change intervals and filter replacement guidelines. Using the wrong API service category or viscosity can lead to premature engine wear, reduced fuel efficiency, and potential warranty voiding.

Engine Coolant

Kenworth (and PACCAR) generally specifies an Extended Life Coolant (ELC) for the T680, which is an Organic Acid Technology (OAT) formula. This coolant is typically red or pink in color.

• Type: PACCAR-approved Extended Life Coolant (ELC) meeting the PACCAR standard. These coolants are designed to provide long-term protection against corrosion, cavitation, and freezing/boiling.

Capacity: The cooling system capacity for a heavy-duty truck like the T680 is substantial, typically ranging from 60 to 70 quarts depending on the specific radiator, heater cores, and auxiliary cooling systems installed.

Intervals and Pitfalls: ELCs have very long service intervals, often up to 600,000 miles or 6 years, with proper maintenance. Crucially, never mix OAT coolants with older Silicate (SCA) or Hybrid Organic Acid Technology (HOAT) coolants. Mixing different coolant technologies can lead to gel formation, additive drop-out, reduced corrosion protection, and severe damage to the cooling system and engine. Always use distilled water if mixing concentrate, though pre-mixed 50/50 solutions are recommended for convenience and purity.

Transmission Fluid

The 2024 Kenworth T680 can be equipped with various transmissions, including Eaton manual transmissions and Allison automatic transmissions.

• Eaton Manual Transmissions (e.g., Fuller Advantage, UltraShift PLUS): Eaton typically specifies their proprietary Eaton PS-386 transmission fluid. This is a synthetic fluid designed for extended drain intervals and improved performance.
• Allison Automatic Transmissions (e.g., T-Series): Allison transmissions require specific high-performance fluids. For most applications in the T680, this will be an Allison TES-295 or the newer Allison TES-668 fluid. TES-668 is backward compatible with TES-295 applications and offers enhanced protection and extended drain intervals. Never use generic "universal" ATF in an Allison transmission.

Capacity: Transmission fluid capacities vary by model. Consult your transmission's owner's manual or data plate.

Intervals and Pitfalls: Follow the manufacturer's recommended drain intervals. For Allison transmissions, fluid analysis can help determine optimal drain intervals, especially with TES-295/TES-668 fluids, which offer very long service lives. Using incorrect fluid will lead to premature wear, shifting issues, and transmission failure.

Rear Differential Fluid

The Kenworth T680 typically uses heavy-duty rear axles from manufacturers like Meritor or Dana.

• Type: Requires an API GL-5 rated gear oil. Common viscosity grades are SAE 75W-90 or 80W-90 synthetic formulations. Some applications, especially those under severe duty or in extremely hot climates, may specify SAE 75W-140. Generally, these axles do not require additional limited-slip differential (LSD) additives as they are typically open differentials or lockers, not clutch-type LSDs. Always verify the specific fluid and viscosity grade with the axle manufacturer's recommendations or your truck's owner's manual.

Capacity: Differential capacities vary significantly by axle model and number of axles. A single rear drive axle might hold 12-18 quarts, while a tandem setup would require more.

Intervals and Pitfalls: Differential fluid intervals are typically long, often aligned with major service intervals due to the robust nature of the fluid and components. Ensure the correct API GL-5 rating is used, as GL-4 fluids are not suitable for hypoid gear designs found in most heavy-duty differentials. Using the wrong viscosity can impact efficiency and lubrication.

Power Steering Fluid

• Type: Most heavy-duty truck power steering systems, including those in the Kenworth T680, specify a fluid that meets Allison C4 requirements. This is often labeled as "Allison Original Equipment Power Steering Fluid" or an equivalent. Some systems may specify a general heavy-duty power steering fluid or in some cases, a Dexron III/Mercon type ATF, but Allison C4 is the most common and safest recommendation.

Capacity: Varies by system complexity but is generally a few quarts.

Intervals and Pitfalls: Power steering fluid is often overlooked. Contaminated or degraded fluid can lead to premature pump and steering gear wear. Check fluid level and condition regularly. If the fluid appears dark or smells burnt, it's time for a flush.

Brake Fluid

The Kenworth T680 primarily uses air brakes. However, if your specific configuration includes a hydraulic braking system (e.g., for certain accessory systems or lighter vocational models), it would typically use DOT 4 brake fluid. Always verify your specific brake system type.

• Type (if hydraulic): DOT 4 Brake Fluid.

Capacity: As required for the specific hydraulic system.

Intervals and Pitfalls: Brake fluid is hygroscopic (absorbs moisture), which lowers its boiling point and can lead to corrosion in the brake system. Hydraulic brake fluid should be flushed periodically, typically every 2 years, regardless of mileage, for optimal safety and component life.

Washer Fluid

• Type: Any commercial-grade windshield washer solvent suitable for automotive use. For cold climates, ensure it has adequate freeze protection.

Capacity: Varies, but typically 1 to 2 gallons.

Intervals and Pitfalls: Keep the reservoir full, especially during long hauls, to ensure clear visibility.

Diesel Exhaust Fluid (DEF)

For all modern diesel engines equipped with Selective Catalytic Reduction (SCR) systems, including those in the 2024 Kenworth T680, Diesel Exhaust Fluid (DEF) is mandatory.

• Type: DEF must meet the ISO 22241 standard. This indicates a high-purity, aqueous urea solution made with 32.5% urea and 67.5% deionized water. It is also often referred to as API DEF to denote compliance with this standard.

Capacity: DEF tank capacities vary but are typically in the 15-20 gallon range, designed to last several thousand miles between refills.

Intervals and Pitfalls: Never use any fluid other than ISO 22241 compliant DEF in the DEF tank. Contaminating the DEF system with water, diesel, or any other fluid will cause severe and costly damage to the SCR system and render the vehicle inoperable. Store DEF properly (between 12°F and 86°F) and check expiration dates, as it can degrade over time. Do not overfill the DEF tank.

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