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Home›Repair guides›Cummins/Onan›Changing Engine Oil and Oil Filter

Cummins/Onan — Changing Engine Oil and Oil Filter

Maintenance

From a Cummins/Onan service manual covering: C13 N6H, C13N6H, C17 N6H, C17N6H, C20 N6, C20N6H, RS13A. Check it applies to your exact model before use.

Applies to: Cummins/Onan C13 N6H, Cummins/Onan C17 N6H, Cummins/Onan C20 N6, Cummins/Onan RS13A

Before you start

  • Contact with used engine oil can cause cancer or reproductive toxicity.
  • Accidental or remote starting can cause severe personal injury or death.

Parts for this job

Part numbers from the service-parts list for Cummins/Onan C20 N6. Verify against your serial number before ordering; some links are affiliate links.

Procedure

  1. Open the generator set's circuit breaker to prevent the ATS from transferring to generator set source when manually starting.
  2. Manually start the generator set and allow it to run 2 to 5 minutes to warm the engine oil.
  3. Remove the access panels to get to the drain hose.
  4. Stop the generator set and allow it to thoroughly cool. Disconnect the battery charger and the negative (–) battery cable.
  5. Open the oil drain cap to release oil from the engine into the appropriate container, close it, and wipe it clean.
  6. Place an appropriate container below the oil filter. Remove the oil filter by turning it counterclockwise and remove the old gasket.
  7. Clean the filter mounting surface on the engine block.
  8. Make sure the gasket is in place on the new filter and apply a thin film of clean oil to the gasket.
  9. Install the new filter until the gasket just touches the block. Turn it an additional 1/2 to 3/4 turn. Do not over-tighten.
  10. Add the appropriate amount of oil and check the engine oil level.
  11. Reconnect the battery cables, positive (+) cable first, and reconnect the battery charger.
  12. Operate the generator set with no load for approximately 5 minutes to check for leaks at the oil filter or oil drain hose.
  13. Shut down the generator set, wait 5 minutes, and confirm the correct oil level. Check for leaks and repair any identified.
  14. Dispose of the used oil and oil filter according to local environmental regulations.
  15. Re-install the access panels and restore the original generator set settings, then close the generator set breaker.

Specs & values

  • Oil level between High and Low marks
  • Access panel fasteners: 5.0 - 6.6 Nm (3.5 - 5.0 ft-lb)

Full service-parts list: Cummins/Onan C20 N6 →

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.

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