Factory-fill conventional engine oil for all Onan gasoline and LP RV generators. Formulated specifically for air-cooled RV generator engines. Supersedes SAE 30 (326-5339).
Cummins OnaMax 10W-30 is the engine oil that all Onan gasoline and LP vapor RV generators are filled with at the factory. Introduced in Q2 2020 as the current standard, it replaced the former SAE 30 (326-5339), which is now obsolete. When you change the oil in your Onan gasoline or LP generator, OnaMax 10W-30 is the oil Cummins recommends you refill it with.
OnaMax 10W-30 is a conventional (non-synthetic) engine oil formulated specifically for air-cooled RV generator engines â protecting against wear, oxidation, and viscosity increase under the elevated temperatures typical of generator operation. Cummins does not recommend synthetic oil for Onan RV generators, noting no long-term benefit for the additional cost.
The exact oil blend used to fill Onan gasoline and LP RV generators during production â same formula, same protection from day one
Specially formulated to resist oxidation and viscosity increase under the elevated temperatures of air-cooled generator operation
Replaces the now-obsolete 326-5339 SAE 30 oil â aligns with current industry standards for small gasoline engines
Suitable for both gasoline and LP vapor-fueled Onan RV generator engines â covers the full KV, KY, HGJAA/HGJAB/HGJAC family and others
OnaMax 10W-30 is for gasoline and LP vapor generators only. For Onan Quiet Diesel (QD/HQD) generators, use OnaMax 15W-40 (326-5366) instead. Always confirm the correct oil for your generator from the Operator's Manual or oil filler cap label.
Cummins has stated that synthetic oil is not recommended for Onan RV generators â there are no long-term benefits over conventional OnaMax oil that justify the additional cost. Use OnaMax conventional oil at the intervals specified in your Operator's Manual.
326-5366 â OnaMax 15W-40 (for Quiet Diesel generators) 326-5365 â OnaFresh GXLP Fuel Stabilizer (for storage) 326-5288 â Onagard Storage Fogging Spray