2022 Kenworth T680 Fluid Specs

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	API CK-4; SAE 15W-40 or 10W-30	10-12 gal (38-45 L) - verify with dipstick
Engine Coolant	ELC (Extended Life Coolant); CAT EC-1, Cummins CES 14603	12-15 gal (45-57 L)
Transmission Fluid	Varies by transmission model	Varies
Rear Axle Fluid	SAE 75W-90 Synthetic Gear Lubricant	3-5 gal (11-19 L) per axle
Brake Fluid	DOT 3 or DOT 4	N/A (Air Brakes)
Power Steering Fluid	SAE 15W-40 Motor Oil or ATF	2-4 qt (1.9-3.8 L)
Windshield Washer Fluid	-	1-2 gal (3.8-7.6 L)
Diesel Exhaust Fluid (DEF)	ISO 22241	15-30 gal (57-114 L)

Engine Oil

The 2022 Kenworth T680 is factory-filled with either PACCAR MX, Cummins X15, or Cummins ISX engines. All of these engines require heavy-duty diesel engine oil meeting API Service Category CK-4. The most common viscosity grades are SAE 15W-40 for all-around performance and SAE 10W-30 for improved fuel economy and cold-weather performance.

• Specification: API CK-4
• Viscosity: 15W-40 or 10W-30
• Capacity: 10-12 gallons (38-45 L), but always verify with the dipstick.

Notes: Using the correct API-licensed oil is critical for the durability of the engine and its aftertreatment system (DPF, SCR). PACCAR-branded oil or any quality brand meeting the CK-4 spec is acceptable.

Engine Coolant

These trucks use a heavy-duty Extended Life Coolant (ELC). Look for coolants that meet CAT EC-1 (Caterpillar) or Cummins CES 14603 specifications. These are typically Nitrite-Free Organic Acid Technology (OAT) coolants.

• Specification: CAT EC-1, Cummins CES 14603
• Type: Nitrite-Free OAT ELC
• Color: Typically red or orange, but do not rely on color alone.

Notes: Never mix coolant types, such as a conventional purple or green coolant with an ELC. Doing so can cause the coolant to gel, leading to blockages and severe engine overheating. Always top-off with the same type of coolant.

Transmission Fluid

Fluid specifications for the T680 vary significantly based on the installed transmission. The two main types are automated manual transmissions (AMTs) and manual transmissions.

• PACCAR TX-12 / Eaton Endurant (Automated): Use a PS-386 specification synthetic fluid.
• Eaton Fuller (Manual): Use a PS-386 or heavy-duty synthetic 50-weight transmission fluid.

Notes: Always check the data tag on the transmission for the exact model and fluid specification. Using the wrong fluid can cause shifting problems and premature wear. "Universal" ATF is not appropriate for these heavy-duty transmissions.

Rear Axle Fluid

Most Kenworth T680s are equipped with tandem rear axles from manufacturers like Meritor or Dana. The standard recommendation is a high-quality, synthetic gear lubricant.

• Specification: API GL-5
• Viscosity: SAE 75W-90

Notes: Ensure the lubricant is approved by the axle manufacturer (e.g., Meritor Spec O76-N, Dana SHAES 256 Rev C). Some applications, especially in heavy-haul or extreme temperature environments, may call for a heavier 75W-140 or 80W-140 fluid. Always check the axle tag or OEM service info.

Brake Fluid

The Kenworth T680 is equipped with a full air brake system. Therefore, it does not use hydraulic brake fluid for its primary service brakes.

Power Steering Fluid

Many heavy-duty trucks, including the T680, use standard heavy-duty engine oil in the power steering system. However, some systems may specify an automatic transmission fluid (ATF).

• Type: SAE 15W-40 Engine Oil or ATF (check reservoir cap or manual)

Notes: Using the wrong fluid can damage the power steering pump and seals. Check the fluid reservoir for markings indicating the correct fluid type.

Windshield Washer Fluid

Use any standard blue, winter-rated (-20°F or lower) windshield washer fluid. For extreme cold, a de-icing or winter-specific blend is recommended.

Diesel Exhaust Fluid (DEF)

All 2022 Kenworth T680s with diesel engines require Diesel Exhaust Fluid (DEF) for the Selective Catalytic Reduction (SCR) system.

• Specification: ISO 22241

Notes: Use only high-quality DEF from a reputable source. Contaminated or poor-quality DEF can destroy the expensive SCR system. Never put anything other than DEF into the DEF tank, which is clearly marked with a blue cap.

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