Peterbilt Model 379 · 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 379
| Fluid | How much | What to buy | Years | Source |
|---|---|---|---|---|
| Engine oil - Series 60 12.7L (pan + filter)Change it: 25,000-35,000 mi by duty | 40 qt (38 L) | API CI-4+ or CK-4, 15W-40 | 2000–2007 | Verified |
| Engine oil - Series 60 14L (pan + filter)Change it: 25,000-35,000 mi by duty | 40 qt (38 L) | API CI-4+ or CK-4, 15W-40 | 2000–2007 | Verified |
| Engine oil - Cummins ISX (pan + filter)Change it: 25,000-50,000 mi by duty | 43.5 qt (41.1 L) steel pan | API CI-4+/CK-4, CES 20086, 15W-40 | 2000–2007 | Verified |
| Engine coolant - SLCChange it: SLC 300,000 mi / 2 yr; ELC 600,000 mi / 4 yr | Not verified - consult OEM service manual | Detroit Power Cool SLC with SCA or ELC | 2000–2007 | Verified |
| Fuel tankChange it: - | 50-180 gal depending on option | Low-sulfur diesel (pre-2007); ULSD 15 ppm (2007+) | 2000–2007 | Verified |
Sources: Cummins ISX Quick Reference Guide 5410641; Detroit DDC-SVC-BRO-0002; Peterbilt 379 specification; Series 60 Operator's Guide DDC-SVC-MAN-0039
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.