Cummins/Onan — Gear Box Lubrication
Maintenance · Reduction gear box
From a Cummins/Onan owner's manual covering: 4UF-3N41, 4UF-3N42, 7UF-3N41, 7UF-3N42, 7UF-3N61. Check it applies to your exact model before use.
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Before you start
- Do not use lubricants commonly known as extreme pressure lubricants, hypoid lubricants, etc.
Procedure
- Remove the breather plug on top of the case and the oil level plug below the shaft.
- Fill the case until the oil just begins to flow from the oil level plug hole.
- Replace plugs.
- Every six months drain the gear box and refill with fresh oil of the recommended grade.
Specs & values
- Gear box holds 1/2 pint U.S.
- Use only SAE #50 motor oil or SAE #90 Mineral Gear Oil
Source: Cummins/Onan owner's 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.