Recommended oil for Cummins RV QG 4000 Generator?

[bcoldpro]

Can I go with 10/30 Oil with an oil change at 45 hours for my onboard generator? I rarely dry camp but will have maybe
a couple of occasions coming up. Potentially cool weather, not freezing.

I live in Southern California and camp locally primarily.

Cummins 15/40 oil is expensive!

 

[Eagle5]

Hi bcoldpro,
You cannot use 10W-30 oil in an engine which requires a 40 weight oil at the top range, because the oil will be too thin at full operating temperature. You can go with a lower first number, or a higher second number, but never the opposite.
I run Mobile One 0W-40 in my generator. It is a universal oil, and can be run in pretty much anything.
If you do not wish to buy the Cummins brand oil, you can buy any good automotive oil. For example, you might purchase 10W-40 oil, which should be readily available, and fairly thrifty.
Eagle5

 

[bcoldpro]

2 Quarts of Cummins 15/40 oil on Amazon is $30!

 

[bcoldpro]

Thank you for your replay and great information