OnaMax™ Oil

Available Q2 of 2020. Cummins will offer the all new SAE10W-30 OnaMax™ oil for Onan RV gasoline and liquefied petroleum (LP) generators. The new oil weight offers the same great benefits you find with our SAE15W-40 product.

  • Identical engine oil blend used in RV generator production.
  • Protects against wear in air- or water-cooled engines.
  • Formulated to give protection against oxidation and increased oil viscosity to help reduce engine wear and oil consumption.
  • Provides excellent protection in water cooled engines where high speeds or longer drain intervals may be experienced.

SAE30 replaced with 10W-30

Cummins is transitioning from SAE30 to SAE10W-30 oil blend starting Q2 2020. This change will align with industry oil standards for small gasoline engines. Cummins manufacturers and ships gasoline and LP powered Onan RV generators using SAE10W-30 oil blend. In addition to the new oil blend, Cummins is still offering the SAE15W-40 for small diesel RV generators.

When ordering your OnaMax™ oil, reference the following part numbers:

  • OnaMax™ SAE10W-30 - part number A063E183
  • OnaMax™ SAE15W-40 - part number 0326-5336
OnaMax oil


Oil changes are important. The first break-in oil change is critical to the longevity of the generator. Use a premium, quality engine oil (such as OnaMax™ SAE10W-30 and SAE15W-40) in the correct oil viscosity for your generator’s typical operating temperature range to provide optimum engine service. Avoid mixing different grades or brands.

It’s good practice to check the oil level daily or every eight hours of operating time. Keep the oil level as near as possible to full, but do not overfill. Overfilling may cause foaming and engine shutdown. Replace the cap tightly to prevent leakage. And if your generator has an oil filter, change it when you change the oil.

DO NOT check the oil level while the generator is running, because hot oil can be thrown out of the dipstick hole, causing severe burns.

  • Gasoline engine oil quality—Use oil meeting any of the following API performance categories: SJ, SL or SM, where SM is currently the highest quality available. Look for the “Energy Conserving” designation to optimize fuel economy.
  • Diesel engine oil quality—Use oil meeting any of the following API performance categories: CF, CF-4, CG-4, CH-4, CI-4 or CJ-4 where CJ-4 is currently the highest quality available. The use of oil meeting API performance category CF-4, CG-4, CH-4 or CI-4 while burning fuel with a sulfuric content greater than 0.5% or CJ-4 while burning fuel with a sulfuric content greater than 0.0015% is not recommended, as oil service is negatively impacted.
  • Cummins does not recommend the use of Synthetic oil in Onan RV generators as there are no long-term benefits for the additional cost.
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