2019 Kenworth T680 Fluid Type Specs

As an ASE-certified master technician, I've compiled a comprehensive guide to all factory-spec fluids for your 2019 Kenworth T680. Adhering to these specifications is crucial for maintaining optimal performance, fuel efficiency, and longevity of your heavy-duty truck.

Quick reference

Fluid	Type/Spec	Capacity (approximate)
Engine Oil	API CK-4 / FA-4 (depending on engine)	38-48 quarts
Engine Coolant	SCA Pre-charged or OAT (verify based on engine)	60-80 quarts
Transmission Fluid	Eaton PS-386, Allison TES-295, or Meritor TP-527 (varies)	13-18.5 gallons
Front Differential	Meritor O-76N, Dana SHAES 256 Rev C	13-17 pints
Rear Differential	Meritor O-76N, Dana SHAES 256 Rev C	18-24 pints
Brake Fluid	DOT 4 (for hydraulic systems, if applicable)	As required
Power Steering Fluid	Eaton PS-164, Dexron-III/Mercon	6-8 quarts
Washer Fluid	Commercial washer fluid	1-3 gallons
Diesel Exhaust Fluid	API certified, ISO 22241	10-20 gallons

Engine Oil

The 2019 Kenworth T680 can be equipped with various engines, primarily the PACCAR MX-13 or Cummins X15. Both engines typically require heavy-duty diesel engine oil rated to API CK-4. Some engines may also be approved for API FA-4, which is a lower viscosity oil designed for improved fuel economy in newer engines. Always verify the specific oil API classification and viscosity (e.g., 10W-30, 15W-40) recommended in your owner's manual for your exact engine configuration and operating conditions.

Intervals: Engine oil and filter change intervals are highly dependent on engine type, duty cycle, and oil analysis results. Kenworth and engine manufacturers provide detailed recommendations, often extending to 50,000 miles or more with synthetic oils and proper filtration. Regular oil analysis is highly recommended for extended drain intervals to monitor oil health and identify potential engine issues.

Pitfalls: Never mix different oil specifications. Using an oil not approved for your engine can lead to premature wear, reduced fuel economy, and potential warranty voidance. Pay close attention to the FA-4 specification; it is not backward compatible with engines not specifically designed for it.

Engine Coolant

Kenworth T680 trucks typically use a heavy-duty diesel engine coolant. Depending on the engine and build, this could be a SCA (Supplemental Coolant Additive) pre-charged conventional coolant (often green or blue-green) or a nitrited OAT (Organic Acid Technology) coolant (often red or pink). It is critical to use the correct type. Refer to your owner's manual or the coolant reservoir cap for the exact specification. Generally, coolants should meet ASTM D6210 for heavy-duty applications.

Intervals: Conventional coolants with SCAs require regular testing and SCA replenishment, with service intervals around 2 years or 100,000 miles. OAT coolants typically offer extended life, often 5 years or 300,000 miles, but still require monitoring.

Pitfalls: Mixing different types of coolants, especially OAT with conventional coolants, can lead to the formation of gels, reduced corrosion protection, and severe engine damage. Always flush the system thoroughly when changing coolant types.

Transmission Fluid

The T680 can be equipped with various transmissions, including Eaton manual and automated manual transmissions (AMT), Allison automatic transmissions, and Meritor manual transmissions. Each requires a specific fluid.

• Eaton Transmissions: Many Eaton manual and AMT transmissions specify Eaton PS-386 fluid, a synthetic transmission fluid designed for extended drain intervals. Some older models might use conventional gear oil. Always verify with your owner's manual.
• Allison Transmissions: Allison automatic transmissions typically require fluids meeting Allison TES-295 (for older models) or Allison TES-668 (for newer models). These are synthetic fluids offering superior performance and extended drain intervals.
• Meritor Transmissions: Meritor manual transmissions often specify Meritor TP-527 synthetic transmission fluid.

Intervals: Transmission fluid intervals vary greatly by type and duty. Eaton PS-386 and Allison TES-295/668 fluids can offer drain intervals up to 500,000 miles or more under ideal conditions, but always follow manufacturer recommendations based on your specific application.

Pitfalls: Using incorrect transmission fluid can lead to premature wear, shifting problems, and catastrophic failure. Never use a "universal" ATF in a heavy-duty truck transmission unless it explicitly meets the OEM specification.

Differential Fluid (Front and Rear)

The Kenworth T680 typically uses Meritor or Dana axles. Both manufacturers have specific requirements for differential gear oil.

• Meritor Axles: Often require a 75W-90 or 80W-90 synthetic gear lubricant specifically formulated for heavy-duty commercial axles, meeting Meritor O-76N specification. Some applications may call for 75W-140.
• Dana Axles: Similar to Meritor, Dana axles typically use a 75W-90 or 80W-90 synthetic gear lubricant, meeting Dana SHAES 256 Rev C specification. Again, 75W-140 may be specified for some severe-duty applications.

Intervals: Differential fluid intervals can be very long with synthetic lubricants, often exceeding 250,000-500,000 miles for line-haul applications. Severe duty or off-road use will necessitate shorter intervals.

Pitfalls: Using conventional gear oil where synthetic is specified can significantly reduce component life. Pay attention to the viscosity and OEM specification. Limited-slip differentials (LSD) are rare in heavy-duty truck axles, but if present, would require a specific additive or fluid.

Brake Fluid

Most modern Kenworth T680 trucks utilize air brake systems, which do not use hydraulic brake fluid. However, if your T680 is equipped with a hydraulic braking system (e.g., for certain support or vocational configurations), it would typically use DOT 4 brake fluid.

Intervals: For hydraulic systems, brake fluid should be flushed and replaced every 2-3 years, as it is hygroscopic and absorbs moisture, which can lead to corrosion and reduced braking performance.

Pitfalls: Never use DOT 5 (silicone-based) fluid in a system designed for DOT 3, 4, or 5.1, as it is not compatible and can severely damage the braking system. Ensure the cap is kept on tightly to prevent moisture absorption.

Power Steering Fluid

The power steering system in a 2019 Kenworth T680 typically uses a heavy-duty power steering fluid. Common specifications include Eaton PS-164 or a fluid meeting Dexron-III/Mercon specifications. Some manufacturers also approve the use of certain heavy-duty engine oils or synthetic transmission fluids for power steering.

Intervals: Power steering fluid generally has a long service life, but it should be checked during routine maintenance. Replacement might be suggested every 100,000-200,000 miles or sooner if contamination is observed.

Pitfalls: Using the wrong type of fluid can cause pump cavitation, seal degradation, and steering system malfunction. Always check your owner's manual for the precise fluid recommendation.

Washer Fluid

Any high-quality, commercially available windshield washer fluid is suitable for your Kenworth T680. Opt for a fluid with antifreeze properties if operating in cold climates to prevent freezing.

Intervals: Replenish as needed.

Pitfalls: Do not use plain water, especially in freezing temperatures, as it can freeze and damage the washer system components.

Diesel Exhaust Fluid (DEF)

For the emissions system, your 2019 Kenworth T680 (if equipped with selective catalytic reduction, SCR) requires Diesel Exhaust Fluid (DEF). This fluid must be API certified and meet the ISO 22241 standard. DEF is a non-toxic solution of 32.5% high-purity urea and 67.5% de-ionized water.

Intervals: DEF is consumed continuously as the truck operates; replenish as needed. The DEF tank size will determine the frequency of refills based on consumption rates.

Pitfalls: Only use API-certified DEF. Never put any other fluid (fuel, coolant, water) into the DEF tank, as it will cause severe damage to the SCR system and lead to costly repairs. Store DEF properly, as it can freeze at 12°F (-11°C) and degrade if exposed to direct sunlight or extreme heat for prolonged periods. The truck's system is designed to handle freezing and thawing of DEF.

Find a trusted shop on Repairius.