2014 Peterbilt 579 Fluid Type Specifications

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	Varies by engine (API CK-4 or FA-4)	Varies by engine (typically 36-48 quarts for Cummins/Paccar)
Engine Coolant	Extended Life Coolant (ELC) - OAT, Red/Purple	Varies by radiator/system configuration (typically 60-80 quarts)
Transmission Fluid	Varies by transmission model (e.g., Eaton PS-386, Allison TES-295, ZF TE-ML 02L)	Varies by transmission model
Front Differential Oil	SAE 80W-90, API GL-5 (or as specified by axle manufacturer)	Varies by axle model
Rear Differential Oil	SAE 80W-90, API GL-5 (or as specified by axle manufacturer)	Varies by axle model
Power Steering Fluid	Eaton PS-164 Rev 7, or as specified by pump manufacturer	Varies by system (typically 4-6 quarts)
Brake Fluid	N/A (Air Brake System)	N/A
Windshield Washer Fluid	All-season washer fluid	Varies
Diesel Exhaust Fluid (DEF)	ISO 22241 (API Certified)	10-20 gallons (typically)

Engine Oil

The 2014 Peterbilt 579 was offered with a variety of engine options, primarily Paccar MX-13 and various Cummins engines (ISX15, ISL9). Therefore, engine oil specifications can vary significantly.

General Specification: For most heavy-duty diesel engines in a 2014 Peterbilt 579, the primary engine oil specification will be API CK-4 or API FA-4. API CK-4 oils offer enhanced oxidation stability, shear stability, and aeration control, making them suitable for a wide range of heavy-duty applications. API FA-4 oils are specifically designed for newer engines to provide improved fuel economy, but they may not be backward compatible with all older engines. Always verify the specific API service category and viscosity grade (e.g., SAE 10W-30, 15W-40) recommended in your engine's owner's manual or on the engine manufacturer's decal.

Capacity: Engine oil capacity is substantial in these trucks, typically ranging from 36 to 48 quarts depending on the specific engine model and oil pan configuration. Always perform a proper dipstick check after an oil change to ensure correct fill levels.

Intervals: Engine oil change intervals can vary widely based on engine manufacturer recommendations, duty cycle, fuel quality, and oil analysis results. Common intervals can range from 20,000 to 75,000 miles or more with oil analysis programs. Refer to your engine's owner's manual for the most accurate service schedule.

Pitfalls: Mixing different oil types or using an incorrect API specification can lead to premature engine wear, reduced fuel economy, and potential warranty issues. Always stick to the manufacturer's recommended specifications.

Engine Coolant

Peterbilt, like most heavy-duty truck manufacturers, primarily utilizes Extended Life Coolant (ELC). This is typically an Organic Acid Technology (OAT) based coolant, often red or purple in color. ELCs provide extended service intervals and excellent corrosion protection without the need for Supplemental Coolant Additives (SCAs).

Specification: Look for coolants that meet the performance requirements of major engine manufacturers like Cummins (e.g., CES 14603, CES 14408) or Detroit Diesel (DDC Power Cool Plus). Always verify the specific Peterbilt or engine manufacturer's coolant specification in your owner's manual.

Capacity: Coolant capacity in a heavy-duty truck can vary significantly based on radiator size, presence of auxiliary coolers, and system plumbing, typically ranging from 60 to 80 quarts (15-20 gallons).

Intervals: ELCs typically have service intervals of 600,000 miles, 12,000 hours, or 6 years, whichever comes first. It's crucial to test the coolant periodically to ensure its integrity.

Pitfalls: Never mix OAT ELC with conventional (green) or Hybrid OAT (HOAT) coolants. Mixing can lead to silicate dropout, gel formation, reduced corrosion protection, and premature wear of water pump seals. Always use distilled or deionized water for dilution if concentrating.

Transmission Fluid

The 2014 Peterbilt 579 could be equipped with a variety of manual, automated manual (AMT), or automatic transmissions from manufacturers like Eaton, Allison, and ZF.

Eaton Transmissions: For Eaton manual and AMT transmissions (e.g., Fuller series), the fluid specification is often Eaton PS-386, a synthetic blend or full synthetic transmission fluid designed for extended drain intervals. Some older Eaton transmissions might specify SAE 50 gear oil. Always check the specific Eaton model for its required lubricant.

Allison Transmissions: For Allison automatic transmissions (e.g., 3000 or 4000 series), the fluid specification will be Allison TES-295 (synthetic) or Allison TES-389 (mineral-based). TES-295 is the preferred choice for extended drain intervals and improved performance. Using a fluid that does not meet the TES-295 specification in an Allison automatic can lead to severe transmission damage.

ZF Transmissions: If equipped with a ZF transmission, the specification could be ZF TE-ML 02L or similar, often a specific synthetic fluid developed for ZF’s products.

Capacity & Intervals: Capacities and service intervals vary significantly by transmission model. Manual and AMT transmissions with PS-386 can have capacities ranging from 12-18 quarts and intervals up to 500,000 miles. Allison automatics typically hold 20-45 quarts and have intervals up to 150,000 miles for TES-295 fluids under normal conditions.

Pitfalls: Using an incorrect or non-spec transmission fluid can cause shifting problems, premature wear, overheating, and eventual transmission failure. Always consult the transmission manufacturer's recommendations.

Front and Rear Differential Oil

The Peterbilt 579 utilizes heavy-duty drive axles that require specific gear lubricants. Common axle manufacturers include Meritor (formerly Rockwell) and Dana (Spicer).

Specification: Most heavy-duty truck differentials specify SAE 80W-90 or SAE 85W-140 gear oil meeting API GL-5 standards. Some high-efficiency or severe-duty applications may call for synthetic SAE 75W-90 or 75W-140. Always verify the specific axle manufacturer's specification or Peterbilt's recommendation, often found on a decal on the axle housing.

Capacity: Differential capacities vary by axle model and housing size. Front axles typically hold 12-18 quarts, while rear drive axles often hold 18-25 quarts (per axle). Tandem drive axles will have two such differentials.

Intervals: Recommended service intervals for differential fluid can range from 100,000 to 250,000 miles, or in some cases even longer with synthetic lubricants and oil analysis.

Pitfalls: Using a non-API GL-5 fluid in a hypoid gear differential can lead to severe damage due to insufficient film strength. Mismatched viscosity or non-OEM-approved fluids can cause overheating and premature wear. Limited-slip differentials, if present, might require a specific friction modifier additive, though this is less common in heavy-duty truck applications than in passenger vehicles.

Power Steering Fluid

Power steering systems in heavy-duty trucks are robust and generally use a specific hydraulic fluid.

Specification: Many Peterbilt trucks specify Eaton PS-164 Rev 7 fluid, which is a high-quality synthetic blend or full synthetic hydraulic fluid. Alternatively, the power steering pump manufacturer (e.g., Sheppard, Ross) may specify a particular hydraulic oil. In some cases, quality automatic transmission fluids (ATF) like Dexron III/Mercon may be acceptable, but always verify this with the manufacturer.

Capacity: Power steering fluid capacity is typically around 4-6 quarts, but can vary with system complexity and reservoir size.

Intervals: Power steering fluid is not always included in routine service intervals, but it's good practice to inspect its condition annually and consider a flush and refill every 100,000-200,000 miles, or if the fluid appears dark or contaminated.

Pitfalls: Using an incompatible hydraulic fluid can lead to pump cavitation, seal degradation, and steering system malfunction. Never use conventional brake fluid in a power steering system.

Brake Fluid

The 2014 Peterbilt 579 uses an air brake system, not a hydraulic brake fluid system like passenger vehicles. Therefore, there is no conventional DOT brake fluid to check or replace. The brake system operates on compressed air.

Pitfalls: If you encounter any issues with braking performance, it's critical to have the air brake system inspected by a qualified heavy-duty technician immediately. Do not attempt to add