2019 Kenworth W900 Fluid Type Specs

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	API CK-4 / FA-4 (varies), SAE 15W-40 typical	Verify with engine manufacturer spec
Engine Coolant	OAT (Organic Acid Technology) fully formulated, ELC (Extended Life Coolant)	12-16 gallons (approximate, varies by engine/radiator)
Transmission Fluid	Varies by transmission model (e.g., Eaton PS-386, Allison TES-295, TES-389)	13.5 - 16 quarts (typical for Eaton/Allison)
Front Differential (if applicable)	SAE 80W-90, API GL-5 (Meritor O76N, Dana SHAES 256 REV C)	10-14 quarts (approximate, varies by axle)
Rear Differential	SAE 80W-90, API GL-5 (Meritor O76N, Dana SHAES 256 REV C)	10-14 quarts per axle (approximate, varies by axle)
Power Steering	Dexron III/Mercon or equivalent; Eaton PS-164 Rev 7	4-6 quarts (approximate)
Brake Fluid	DOT 3 or DOT 4 (hydraulic systems only)	As needed
Windshield Washer Fluid	Commercial washer fluid	1-2 gallons (approximate)
Diesel Exhaust Fluid (DEF)	ISO 22241-1 compliant	10-20 gallons (approximate)

Engine Oil

For a 2019 Kenworth W900, the specific engine oil type and capacity will depend heavily on the installed engine. Kenworth W900s are typically equipped with Cummins or PACCAR engines.

Type/Spec: The primary specification for diesel engine oil in this class is API CK-4 or API FA-4. It is crucial to consult your engine's owner's manual or the OEM service information to determine the exact specification recommended for your specific engine and operating conditions. FA-4 oils are specifically designed for newer engines to improve fuel economy but are not backward compatible with all older engines. CK-4 oils offer improved oxidation stability, shear stability, and aeration control compared to previous categories.

Viscosity: A common viscosity grade for heavy-duty diesel engines in a wide range of climates is SAE 15W-40. However, depending on your operating temperature range, engine manufacturer recommendations might include other viscosities such as 10W-30 or 5W-40.

Capacity: Engine oil capacity varies significantly by engine model. A Cummins X15, for example, might hold upwards of 10-12 gallons (approximately 40-48 quarts), while a PACCAR MX-13 could be similar. Always verify the exact capacity in your owner's manual.

Intervals and Pitfalls: Engine oil change intervals for heavy-duty trucks can range from 20,000 miles to well over 50,000 miles, or even longer with oil analysis programs. Adhering to the manufacturer's recommended interval or using an oil analysis program is vital to engine longevity. Using the incorrect API specification (e.g., using FA-4 in an engine not designed for it) can lead to premature wear. Always use oil that meets or exceeds the engine manufacturer's specifications.

Engine Coolant

Type/Spec: The 2019 Kenworth W900 typically uses an Extended Life Coolant (ELC), which is an Organic Acid Technology (OAT) formula. These coolants are usually red, pink, or sometimes purple, though color should never be the sole indicator of coolant type. They are fully formulated and do not typically require Supplemental Coolant Additives (SCAs) at regular intervals once initially filled. Kenworth often recommends coolants meeting standards like ASTM D6210 or specific OEM specifications provided by the engine manufacturer (e.g., Cummins CES 14603 or PACCAR PCS-1).

Capacity: The cooling system capacity widely varies depending on the engine, radiator size, and chassis configuration, but it typically ranges from 12 to 16 gallons.

Intervals and Pitfalls: ELC coolants offer extended service life, often up to 600,000 miles or 6 years, whichever comes first, before a full flush and fill is recommended. However, it's crucial to test the coolant annually for proper freeze point, boiling point, and to ensure it still meets protective additive levels. Never mix different types of coolants, especially OAT with conventional Inorganic Acid Technology (IAT) or Hybrid Organic Acid Technology (HOAT) coolants, as this can lead to additive dropout, gelling, and severe damage to the cooling system and engine. Always use distilled or deionized water if mixing concentrate.

Transmission Fluid

Type/Spec: Transmission fluid type for a 2019 Kenworth W900 is entirely dependent on the specific transmission installed. Common transmissions include Eaton (manual and automated manual transmissions like Fuller Advantage or Ultrashift) and Allison (automatic transmissions like the HD or RDS series).

• Eaton Transmissions: Many Eaton manual and automated manual transmissions specify Eaton PS-386 fluid, which is a synthetic transmission lubricant. Some older or specific models might use an API GL-4 SAE 50 synthetic manual transmission fluid.
• Allison Transmissions: Allison automatic transmissions typically require fluids meeting Allison TES-295 or TES-389 specifications for synthetic automatic transmission fluid. These are typically heavy-duty synthetic fluids designed for extended drain intervals and improved performance.

Capacity: Capacity varies significantly. Eaton transmissions can hold around 13.5 to 16 quarts. Allison transmissions can range from 19 quarts to over 40 quarts depending on the model and external coolers. Always consult the transmission manufacturer's specific documentation.

Intervals and Pitfalls: Adhere strictly to the transmission manufacturer's fluid and filter change intervals. Using incorrect fluid can lead to premature wear, shifting issues, and catastrophic failure. Universal ATFs are generally not recommended for heavy-duty applications where specific OEM specifications exist.

Differential Fluid (Front and Rear)

Type/Spec: Kenworth W900s utilize heavy-duty drive axles from manufacturers like Meritor and Dana. Generally, they specify a SAE 80W-90 or SAE 85W-140 gear oil, meeting API GL-5 standards. Some manufacturers may have their own specific proprietary specifications such as Meritor O76N or Dana SHAES 256 REV C for extended drain intervals. For severe service or higher temperatures, a synthetic 75W-90 or 75W-140 might be recommended. Limited-slip differentials, if equipped, would require an LS additive or a fluid already formulated with one.

Capacity: Each differential (front drive axle, rear drive axle) can hold approximately 10-14 quarts, but this varies by axle model and housing size. Tandem axle configurations will have separate capacities for each axle.

Intervals and Pitfalls: Differential fluid intervals can be quite long, especially with synthetic gear oils meeting OEM extended drain specifications, often ranging from 250,000 to 500,000 miles. However, severe service conditions, such as continuous heavy hauling or extreme temperatures, may necessitate shorter intervals. Always check for leaks and maintain proper fluid levels. Using the wrong weight or specification can impact fuel economy and component life.

Power Steering Fluid

Type/Spec: For a 2019 Kenworth W900, the power steering system typically specifies an automatic transmission fluid (ATF) type fluid, such as Dexron III/Mercon or a heavy-duty power steering fluid that meets Eaton PS-164 Rev 7 (for systems with Eaton components) or equivalent specifications.

Capacity: Power steering fluid capacity is typically around 4-6 quarts, but can vary slightly depending on the steering gear and hydraulic lines.

Intervals and Pitfalls: Power steering fluid is often overlooked. While not as frequent as engine oil, it should be checked and replaced periodically, often every 100,000-150,000 miles or if fluid appears dark or contaminated. Using incorrect fluid can lead to pump whine, steering difficulty, and premature component failure.

Brake Fluid (for hydraulic brake systems)

Type/Spec: Most heavy-duty trucks utilize air brake systems. However, if your Kenworth W900 is equipped with a hydraulic braking system (less common for class 8 trucks but possible for certain configurations), it would typically use DOT 3 or DOT 4 brake fluid. DOT 4 has a higher boiling point than DOT 3, offering better performance under heavy braking. DOT 5.1 is also compatible with DOT 3/4 systems and offers even higher boiling points, but it is not silicone-based like DOT 5.

Capacity: As needed to fill the master cylinder and lines. Brake fluid is not consumed in a properly functioning system.

Intervals and Pitfalls: Brake fluid is hygroscopic, meaning it absorbs moisture over time, which lowers its boiling point and can lead to corrosion. It should be flushed and replaced every 2-3 years, or as recommended by the manufacturer. Never use DOT 5 (silicone-based) fluid in a system designed for DOT 3/4/5.1, as they are incompatible and will cause seal damage and system failure.

Windshield Washer Fluid

Type/Spec: Any commercially available windshield washer fluid is suitable for a 2019 Kenworth W900. These typically contain a mixture of water, alcohol (for freeze protection), and detergents.

Capacity: Washer fluid reservoir capacity is generally around 1-2 gallons.

Intervals and Pitfalls: Top off as needed. In colder climates, ensure the fluid provides adequate freeze protection to prevent the reservoir and lines from freezing and potentially bursting.

Diesel Exhaust Fluid (DEF)

Type/Spec: For any modern diesel truck equipped with Selective Catalytic Reduction (SCR) technology, including the 2019 Kenworth W900, Diesel Exhaust Fluid (DEF) is required. The DEF must meet ISO 22241-1 specifications. This ensures the correct concentration (32.5%) of high-purity urea in de-ionized water.

Capacity: DEF tank capacities typically range from 10 to 20 gallons or more, providing a range of several thousand miles between fill-ups.

Intervals and Pitfalls: DEF is consumed in proportion to fuel usage. It is critical to only use ISO 22241-1 certified DEF. Using non-compliant DEF, water, or other fluids, or allowing the DEF tank to run dry, will activate engine derates and potentially damage the SCR system, leading to costly repairs. Store DEF properly as it has a shelf life and can be affected by extreme temperatures and contamination.

Find a trusted shop on Repairius.