Onan OnaMax SAE 15W-40 Engine Oil, 32 oz.

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.

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.

No issues

I had trouble finding the exact spec motor oil for my Onan 4000 generator. This is OEM spec from Onan, so I used it in my generator's first oil change. I will be using it from now on.

Onan calls for this oil but price I paid is obscene. We were leaving on a trip and through my own fault I was unable to buy this less expensive with lead times. Came very close to putting Valvoline in but then would have had to change again once Onan oil arrived. Again, the price is 100% where my dissatisfied lies. Product is good!