Cummins/Onan — Reduction Gear Drive Oil Change
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan CCK engine
Before you start
- Do not use extreme pressure or hypoid lubricants.
Procedure
- Drain gear box after first 100 hours.
- Refill with SAE 50 motor oil or SAE 90 mineral gear oil.
- Repeat every six months or 100 hours.
- Remove filler plug and oil level plug.
- Fill until oil flows from level plug hole.
- Replace both plugs.
Tools required
- wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Gear box capacity 1/2 pint US (0.24 L)
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.