Cummins/Onan — Changing Engine Oil
Maintenance
From a Cummins/Onan owner's manual covering: 3.3 KY, 3.6 KY, 4.0 KY. Check it applies to your exact model before use.
Applies to: Cummins/Onan 3.6 KY, Cummins/Onan 4.0 KY
Before you start
- Crankcase pressure can blow hot oil out the fill opening, causing severe burns
- Used engine oil can cause cancer or reproductive toxicity
Procedure
- Run the generator set under load until at operating temperature, stop it, disconnect negative battery cable
- Remove the oil fill cap
- Place a pan under the oil drain plug and remove the plug with a socket, drain all oil
- Replace the plug and tighten to 27 Nm (21 ft-lbs)
- Refill with oil per Oil Change Values; check level and add or drain as necessary
- Screw the oil fill cap on securely
- Reconnect the negative battery cable
- Run the generator a few minutes, shut down, recheck oil level and leaks
- Dispose of used oil per local regulations
Tools required
- 14 mm socket Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Oil amount 1.5 liters (1.6 qt)
- Drain plug torque 27 Nm (21 ft-lbs)
Full service-parts list: Cummins/Onan 3.6 KY →, Cummins/Onan 4.0 KY →
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.