Peterbilt Model 579 · fluids
Fluids & Fill AmountsHow much oil, coolant, DEF and gear oil this truck takes, and what specification to buy.
Set the year first
Then read the How much column as a refill quantity, not a dry fill. Fill to the dipstick or sight glass and treat the number as a starting point — a drain never gets everything out.
Fill amounts for Peterbilt Model 579
| Fluid | How much | What to buy | Years | Source |
|---|---|---|---|---|
| Engine oil - PACCAR MX-13 (pan + new filters)Change it: 75,000 mi line haul; 50,000 mi high idle; 30,000 mi severe | 42 U.S. qt (40.0 L) | API CK-4 / FA-4 | 2017–2026 | Verified |
| Engine oil - Cummins X15 (if fitted)Change it: 25,000-60,000 mi by duty cycle | 43.4 qt (41.1 L) steel pan / 45.4 qt (43.0 L) aluminum pan | API CK-4, CES 20086 | 2017–2026 | Verified |
| Engine coolantChange it: Test at PM | Approx. 13 gal (49 L) | OAT extended-life, min 15 psi cap, 223 F max outlet | 2017–2026 | Verified |
| Diesel exhaust fluid (DEF) tankChange it: Fill at every fuel stop | 10.2 gal (38.6 L) small to 20.1 gal (76.1 L) large, by tank option | ISO 22241 DEF | 2021–2026 | Verified |
| Fuel tankChange it: - | 40-150 gal (151-568 L); 20 in, 23 in or 26 in diameter | ULSD, 15 ppm max | 2021–2026 | Verified |
| Transmission - PACCAR TX-12 PROChange it: Not verified - consult OEM service manual | Not verified - consult OEM service manual | PACCAR-approved synthetic | 2021–2026 | Unconfirmed |
| Rear axle - PACCAR DX-40 tandemChange it: Not verified - consult OEM service manual | Not verified - consult OEM service manual | API GL-5 synthetic | 2013–2026 | Unconfirmed |
| Power steeringChange it: Check at PM | Not verified - consult OEM service manual | ATF per steering gear specification | 2013–2026 | Unconfirmed |
Sources: Cummins Quick Reference Guide 5410641 (X15 EPA 2017); PACCAR MX-13 Operators Manual Y53-1100-1F1, Table 2; PACCAR MX-13 Operators Manual, Table 6; Peterbilt 2024 Heavy Duty Body Builder Manual Rev A
Two ways to wreck an engine in five minutes
Overfilling an oil pan aerates the oil and can damage bearings. Running a cooling system low can crack a liner or a head before the gauge even moves. Fill slowly, then check the dipstick or sight glass twice.