2018 Peterbilt 579 — Oil Capacity & Filter Specs

The 2018 Peterbilt 579 takes 10–11 gallons (about 40–44 quarts, 38–42 liters) of engine oil with filter, depending on whether it’s equipped with the PACCAR MX‑13 or the Cummins X15/ISX15 and which oil pan is fitted.

Quick answer

• Oil capacity: 10–11 gal (40–44 qt; 38–42 L) with filter; verify by engine and oil pan option
• Recommended oil weight: 10W‑30 (preferred for 2017+ EPA engines) or 15W‑40 based on climate and duty
• Oil type/spec: API FA‑4 (fuel‑economy) or API CK‑4 (widely approved); Cummins CES 20086 (FA‑4) / CES 20081 (CK‑4) compliant oils are recommended; PACCAR approves API CK‑4/FA‑4 for MX‑13
• Oil filter (varies by engine):
  • Cummins X15/ISX15: OEM Cummins/Fleetguard LF14000NN; common aftermarket: WIX 57712, Donaldson P551808; Fram/Mobil 1 typically do not list a direct HD equivalent—use heavy‑duty lines (Fleetguard/Donaldson/Baldwin/WIX)
  • PACCAR MX‑13: OEM filter part number varies by engine serial and oil module—consult Peterbilt/PACCAR with VIN; use a premium HD filter meeting OEM spec

Capacity by engine option

Oil change interval

• Normal duty (line‑haul, steady highway, low idle time, good fuel economy):
  • Cummins X15: typically up to 60,000 miles (96,000 km) with approved FA‑4/CK‑4 oils when operating conditions and fuel economy targets are met. Follow the Cummins interval table by duty cycle and fuel economy, or use oil analysis.
  • PACCAR MX‑13: commonly 40,000–60,000 miles (64,000–96,000 km) depending on fuel consumption and duty cycle. Follow the PACCAR maintenance schedule or oil analysis.
• Severe duty (high idle time, frequent PTO, stop‑and‑go, dusty or extreme temp operation): 15,000–25,000 miles (24,000–40,000 km) is typical for either engine. Use oil analysis to optimize.

Tip: Heavy‑duty OEMs base intervals on fuel burned and duty cycle. If you don’t track fuel‑to‑drain, default to the conservative end of the ranges above or sample oil at mid‑interval.

Drain plug torque

• Cummins X15/ISX15: 44 ft‑lb (60 N·m) typical for the oil drain plug. Verify by oil pan manufacturer and plug size.
• PACCAR MX‑13: commonly in the 44 ft‑lb (60 N·m) range. Verify against the specific pan/plug fitted to your engine.

Crush washer/seal note: Many Class‑8 pans use an O‑ringed or sealing‑washer plug. Always replace the sealing washer or O‑ring if equipped and inspect threads. Do not over‑torque—large‑format plugs can strip pans.

How to change the oil

1. Warm the engine to operating temperature, then shut down and chock wheels.
2. Place a suitable catch container (12+ gal capacity) under the drain. Remove the drain plug and let oil fully drain.
3. Remove and replace the oil filter(s). Lightly oil the new filter gasket(s) and spin on to gasket contact, then tighten per filter maker’s instruction (usually 3/4–1 turn after contact) or torque if specified.
4. Reinstall the drain plug with a new sealing washer/O‑ring (if used) and torque to spec.
5. Fill the crankcase with 9.5–10 gal of the correct oil, start the engine, check for leaks, shut down, wait a few minutes, then top off to the dipstick full mark. Record total fill for your truck.
6. Reset any maintenance reminders and record mileage/hours/fuel‑to‑drain.

Common issues / tips for this generation

• Oil spec choice (FA‑4 vs CK‑4): 2017+ X15 and MX‑13 generally allow FA‑4 10W‑30 for best fuel economy, but some fleets prefer CK‑4 (10W‑30 or 15W‑40) for mixed equipment or severe duty. Use an oil meeting Cummins CES 20086 (FA‑4) or 20081 (CK‑4) and match to your duty cycle and ambient temps.
• Fuel dilution from extended idling/regeneration: High idle/PTO time and frequent DPF regens can raise fuel dilution. Shorten intervals or use oil analysis if idle exceeds ~30% of engine hours.
• Crankcase ventilation filter: Both MX‑13 and X15 use serviceable CCV/vent filters. A restricted filter can increase crankcase pressure and oil leaks—replace per the maintenance schedule.
• Leaks at oil cooler/lines and oil pan: Inspect cooler housings, gaskets, and pan rails during each service; address seeping early. Replace drain plug seals proactively.
• Always verify capacity by dipstick: Sump sizes vary. After refill, run, let oil settle, and set the level to the full mark—do not rely solely on a published number.
• Extended drains require data: To push beyond the conservative ranges above, implement oil analysis (soot, oxidation, TBN, viscosity, fuel dilution) and track fuel burned between services.

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