Cummins/Onan 20W-20 — Break-In Procedure
Operation · Engine
For the Cummins/Onan 20W-20, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 20W-20, Cummins/Onan RDJF engine
Before you start
- Continuous running under one half load during first few hundred hours may cause poor ring seating.
Procedure
- Run one half hour at 1/2 load.
- Run one half hour at 3/4 load.
- Run at full load.
- Drain and replace crankcase oil after first 50 hours; drain while still hot.
Full service-parts list: Cummins/Onan 20W-20 →
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.