2021 Peterbilt 579 Oil Capacity & Filter Specs

The 2021 Peterbilt 579, when equipped with the PACCAR MX-13 engine, takes approximately 44 quarts (42 liters) of oil, including the filter. For the Cummins X15 engine, the capacity is 14 gallons (52.8 liters). Always verify the dipstick reading after filling.

Quick Answer: 2021 Peterbilt 579 Oil Specs

• Oil Capacity (PACCAR MX-13): 44 quarts / 42 liters (with filter)
• Oil Capacity (Cummins X15): 14 gallons / 52.8 liters (with filter)
• Recommended Oil Weight: 15W-40 or 5W-40 Synthetic (check your manual for temperature-specific requirements)
• Oil Specification: API CK-4
• OEM Oil Filter (PACCAR MX-13): 2296555PE
• Aftermarket Cross-Reference (PACCAR MX-13):
  • Wix: WL10132
  • Fram: CH11781
  • Donaldson: P551100
• OEM Oil Filter (Cummins X15): LF14000NN
• Aftermarket Cross-Reference (Cummins X15):
  • Wix: WL10103
  • Fram: HPH9713
  • Mobil 1: M1-901

Capacity by Engine Option

The 2021 Peterbilt 579 was offered with two primary engine choices, each with a different oil capacity.

Oil Change Interval

Oil change intervals for heavy-duty trucks like the Peterbilt 579 are highly dependent on usage, idle time, and fuel consumption. Modern engine management systems will often calculate the ideal interval for you. Always consult your owner's manual and follow the oil life monitor if equipped.

• Normal Duty: For the PACCAR MX-13, PACCAR recommends oil and filter changes up to 75,000 miles, depending on fuel consumption and oil analysis. For the Cummins X15, intervals can also extend to 75,000 miles under ideal conditions.
• Severe Duty: This includes frequent short trips, extensive idling, dusty conditions, or heavy loads. Under these conditions, the interval should be shortened significantly. A common severe-duty interval is 25,000-30,000 miles, but regular oil analysis is the best way to determine a precise schedule.

Drain Plug Torque

Proper torque on the oil drain plug is critical to prevent leaks and stripped threads.

• PACCAR MX-13 Drain Plug Torque: 63 ft-lbs (85 Nm). Always use a new crush washer to ensure a proper seal.
• Cummins X15 Drain Plug Torque: 60 ft-lbs (81 Nm). Always use a new crush washer.

How to Change the Oil (Simplified)

Changing the oil on a Peterbilt 579 is a straightforward but large-scale job.

1. Run the engine for a few minutes to warm the oil.
2. Position a large drain pan (at least 15-gallon capacity) under the oil pan.
3. Remove the drain plug and allow the oil to drain completely.
4. Remove the oil filter. Be prepared for additional oil spillage.
5. Clean the drain plug and the filter housing mating surface.
6. Lubricate the new filter gasket with fresh oil and install the new filter.
7. Install the drain plug with a new crush washer and torque to spec.
8. Fill the engine with the specified amount and type of new oil.
9. Start the engine, let it run for a minute, then shut it off.
10. Wait a few minutes for the oil to settle, then check the dipstick and top off as needed.

Common Issues & Tips

• Oil Sampling is Key: For a truck that is a primary business tool, regular oil analysis (every oil change) is a cheap insurance policy. It can identify fuel dilution, coolant leaks, and premature wear before they become catastrophic failures.
• Check for Leaks: The PACCAR MX-13 can be prone to valve cover and oil pan gasket leaks. When performing an oil change, take a moment to inspect these areas for any signs of seepage.
• Filter Pre-Fills: There is much debate on pre-filling filters. While it can speed up the process of building oil pressure on startup, it also risks introducing unfiltered oil or contaminants into the engine. If you do pre-fill, pour the oil into the outer ring of holes, not the center.
• Correct Dipstick Reading: Due to the large sump size, it's important to let the oil settle for at least 20-30 minutes before taking a final dipstick reading for the most accurate result.

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