Peterbilt Model 387 · 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 387
| Fluid | How much | What to buy | Years | Source |
|---|---|---|---|---|
| Engine oil - PACCAR MX-13 (pan + new filters)Change it: 30,000-75,000 mi by duty | 42 U.S. qt (40.0 L) | API CK-4/FA-4, 10W-30 or 15W-40 | 2010–2018 | 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 | 2006–2017 | Verified |
| Engine coolantChange it: Test at PM | Approx. 13 gal (49 L) | OAT extended-life, min 15 psi cap | 2006–2018 | Verified |
| DEF tankChange it: Fill at every fuel stop | 7-11 usable gal depending on option | ISO 22241 DEF | 2010–2018 | Verified |
| Fuel tankChange it: - | 75-180 gal depending on option | ULSD, 15 ppm max | 2006–2018 | Verified |
Sources: Cummins ISX Quick Reference Guide 5410641; PACCAR MX-13 Operators Manual Y53-1100-1F1; PACCAR MX-13 Operators Manual, Table 6; Peterbilt 387 specification
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.