Storage Maintenance For Onan Quiet Series on Board Generator

Updated 02/23/2026 | Published 02/19/2026

Question:

What are the maintenance requirements needed before winter storage?

asked by: Al

Expert Reply:

Hi Al,

There’s definitely a bit of preparation involved when storing your Cummins Onan for an extended period. Gasoline RV generators like the Cummins Onan Quiet Series 4,000-Watt part # CM32ZR need some attention before long-term storage because gasoline can break down over time and form varnish, which can clog the carburetor, fuel filter, and fuel pump if it sits too long. Adding a fuel stabilizer to fresh fuel and then running the generator for about 30 minutes allows the treated fuel to circulate through the system and helps prevent that buildup during storage.

Beyond fuel treatment, Onan’s winterizing guidelines recommend changing the oil and filter, then running the generator under load to help remove moisture and condensation from the system. It’s also a good idea to disconnect the battery to prevent drain and cap the exhaust outlet to keep out dirt and critters. They also advise draining the carburetor float bowl or using engine fogging oil while the unit is running to coat internal components and reduce the risk of corrosion during long-term storage.

I have attached snips from the instructions for more detailed instructions.

expert reply by: Heather A