Cummins/Onan B43 / B48 — Crankcase Oil Change
Maintenance · oil system
For the Cummins/Onan B43 / B48, from the Cummins/Onan service manual.
Applies to: Cummins/Onan B48
Before you start
- Crankcase pressure can blow out hot oil, which can cause severe personal injury. Do not check oil while engine is running.
- Hot crankcase oil can cause burns. Wear protective clothing and keep hands clear when draining oil.
- Do not overfill crankcase.
Parts for this job
Part numbers from the service-parts list for Cummins/Onan B48. Verify against your serial number before ordering; some links are affiliate links.
Procedure
- Run engine until thoroughly warm before draining oil.
- Stop engine, place a pan under the drain outlet and remove the oil drain plug.
- After oil is completely drained, clean and replace the drain plug.
- Fill crankcase with correct amount of oil; refer to SPECIFICATIONS for capacity.
- Use oils meeting API classification SF, SF/CC, or SF/CD.
- Refer to chart to determine proper viscosity grade.
- Check oil level to FULL mark of dipstick.
- Start engine and run a short time to check for oil leaks around drain plug.
Specs & values
- Oil capacity 1.7 qts (1.6 litre) without filter
Full service-parts list: Cummins/Onan B48 →
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.