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⚡ Power your generator with the oil it deserves—because your RV’s heart beats Onan!
Onan OnaMax SAE 15W-40 Engine Oil is a premium conventional oil specially formulated to reduce high-temperature oxidation and engine wear. Factory-tested and recommended by Cummins, it ensures optimal performance and longevity for Onan generators. Packaged in a convenient 32 oz. bottle, it’s the trusted choice for RV owners who demand reliability and precision.
| ASIN | B00278MET8 |
| Automotive Fit Type | Vehicle Specific Fit |
| Best Sellers Rank | #4,646 in Automotive ( See Top 100 in Automotive ) #88 in Motor Oils |
| Brand | Cummins |
| Brand Name | Cummins |
| Compatible with Vehicle Type | Generator |
| Container Type | Bottle |
| Customer Reviews | 4.8 out of 5 stars 1,052 Reviews |
| Global Trade Identification Number | 00690781000704 |
| Included Components | Oil |
| Item Type Name | Oil |
| Item Weight | 1.92 Pounds |
| Liquid Volume | 1 Liters |
| Manufacturer | Cummins |
| Manufacturer Part Number | 326-5336 |
| Model Number | 326-5336 |
| Package Information | Bottle |
| SAE J300 Viscosity Grade | 15W-40 |
| Size | 32 oz |
| UPC | 690781000704 |
| Unit Count | 32.0 Fluid Ounces |
| Vehicle Service Type | Generator |
| Viscosity Level | Medium to High |
J**N
The Right Oil for My Onan RV Generator – Won't Use Anything Else
When it comes to keeping my Onan RV generator running at its best, I trust OnaMax SAE 15W-40 and nothing else. Using the manufacturer-recommended oil just makes sense—it's specifically formulated for Onan generators and gives the peace of mind that comes with knowing you're putting the right product in a piece of equipment you depend on. The 15W-40 viscosity handles the heat and demands of generator use well, and after oil changes with this product the generator starts reliably and runs smoothly without hesitation. For RV use where the generator gets regular workouts powering appliances, AC units, and other loads, using the correct oil is one of the simplest and most important things you can do to protect your investment and extend the life of the engine. If you own an Onan RV generator and want to do right by it, skip the guesswork and use the oil that's made for it. This is a no-brainer purchase that I'll keep on my regular maintenance supply list.
F**R
Oil
Great quality / price value
J**E
Only use ONAN products on ONAN generators!
One thing I've learned after buying an RV is that the ONAN generators are very particular. I only use ONAN product/parts. This oil is a little pricey but is excellent quality and what ONAN recommends.
R**S
Recommend by Onan
Recommend by Onan for first 20 hr oil change on our 5500 generator.
C**S
Good
Good
D**N
Perfect for my RV cummins 7000 generator
Perfect for my RV generator. I don't know why but you can't purchase this product at a automotive store. Only Amazon or Cummins.
T**M
Great price
Im a stickler for using original equipment or recommend parts
A**R
No issues
No issues
Trustpilot
3 weeks ago
3 days ago