Oil capacity varies by variant: 9.5 L (4BTA-3.9-G2), 11 L (4BTA3.9), 11 L (4BTA3.9-G11), 11.5 L (4BTA3.9-G3). The Cummins/Onan 4BTA3.9 engine line groups 8 variant designations. Parts and fitment are pooled here so a cross-reference found on one variant surfaces for the whole family.
| Variant | Displacement | Cylinders | Rated rpm | Oil capacity | Coolant |
|---|---|---|---|---|---|
| 4BTA 3.9-G4 | 3.9 L | 4 | 1,800 | — | 7.9 L |
| 4BTA-3.9-G2 | 3.9 L | 4 | 1,500 | 9.5 L (10.0 qt) | 21 L |
| 4BTA3.9 | 3.9 L | — | 1,800 | 11 L (11.6 qt) | 22 L |
| 4BTA3.9-G11 | 3.9 L | — | 1,500 | 11 L (11.6 qt) | 7.5 L |
| 4BTA3.9-G3 | 3.9 L | — | 1,800 | 11.5 L (12.2 qt) | 17.7 L |
| 4BTA3.9G1 | 3.9 L | — | — | — | — |
Each figure is from that variant’s own documents (see its engine page for sources). Oil capacity can differ between applications of the same engine; check the manual for your generator set.
| Part # | Description | Category |
|---|---|---|
| 0140-3550 | Air Cleaner Element | Air filter |
| 0140-3553 | Air Cleaner (Heavy Duty) | Air filter |
| 0140-3590 | Element Air Cleaner | Air filter |
| 0140-3880 | Element Air Cleaner (Safety) | Air filter |
| 0133-0228 | Heater Kit (Alternator 240V) | Alternator |
| 0133-0229 | Heater Kit (Alternator 110V) | Alternator |
| FS3345 | Fuel - Filter | Fuel filter |
| 0501-0830 | Line - Oil (5/8" 15.9 Bore) | Hose |
| 0501-0841 | Line - Fuel | Hose |
| 0501-0842 | Line - Fuel | Hose |
| 0503-2462 | Hose | Hose |
| 0503-2466 | Hose - Air | Hose |
| 0503-2474-12 | Hose - Steam | Hose |
| 0503-2474-25 | Hose - Steam | Hose |
| 0503-2542 | Elbow - Hose | Hose |
| 0541-1115 | Hose Kit (c/w Clamps) | Hose |
| LF1251 | Oil - Filter | Oil filter |
| 0102-1448-02 | Adapter - Oil Drain | Service part / kit |
| 0130-6000 | Fan - Radiator | Service part / kit |
| 0159-1552 | Cap-Filler (fuel tank) | Service part / kit |
| 0333-0690 | Heater-Engine Coolant-240v. | Service part / kit |
| 0333-0699 | Heater-Engine Coolant-120v. | Service part / kit |
| 0416-1208 | Battery | Service part / kit |
| 0504-0254 | Valve - Gate (M18 x 1.5) | Service part / kit |
| 0541-1119 | Radiator Cap | Service part / kit |
| 0541-1120 | Drain Valve | Service part / kit |
| 0150-2201 | Speed Sensor - Magnetic | Sensor |
| 0159-1619 | Indicator Fuel (230 LG) | Sensor |
| 0193-0444 | Sender - Oil Pressure | Sensor |
| 0193-0468 | Sender - Low Coolant | Sensor |
| 0193-0529-01 | Sensor - Temperature | Sensor |
| 0309-0707-01 | Fuel Level Switch | Sensor |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.