Is it normal for an Onan generator to use a quart of oil every 50 hours?  I am using 10W-40 castrol motor oil.


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I think that your Onan calls for straight 30W oil.Unless its being used below 35F.

Well it is a moot point now, the generator started ratting and banging and then quit running.  It turns over but will not start. Another thing added to my to-do-list. 

Air cooled engines need a heavier oil.They use the oil to help cool the engine more then water cooled engines.I use Mobile 1 EP oil and filters in most of my stuff.Even in my air cooled zero turn mower,using the correct weight oil.

Depending on what year the Onan is, They mostly use an HD30 or 40 and even 50 weight motor oil. (H D Heavy Duty) Also depends on climate as well. Mine uses about a half a quart in 75hrs. I was told that it is perfectly normal. THEY CAN USE UP TO A QUART IN 50HRS and be normal. using a multi viscosity oil you will defiantly use oil, it becomes toooo thin, and therefor will burn a little. Consult your local Onan dealer  and ask them and they will point you in the right direction. or you can friend me, and I will dig a little deeper for you, I will need to know year, KW, and climate you are in. . Mike

Thanks for the offer Mike, but right now the genny is not running, the engine turns over just fiine, but there is no starting it.  I think the generator portion of the genny is seized, because there is a strange sound coming from there just about the time the engine tries to catch and run.  

As for climate, we vary widely from the heat and humidity of Arkansas (where we live) to the high mountains of the rockies.  I figure once I get it running again I will use 40 or 50w oil in the summer and 30w in the winter.

Depending on the age and model, maybe not that unusual. Does it smoke?

It is an 86 K5000 and no it does not smoke.

correction, it is a kw6.5

Then, if there's no smoke and no massive amount of oil leaks, I would live with the oil usage and be happy!

I am not complaining about the oil consumption, just wanted to know if it was normal, we never had a generator in any of our TTs so this is a new experience for us.

As long as we had to take our MH to the repair shop I had them look at the generator and figure out why it was not running, they found that the pilot bearing at the end of the generator portion of the generator had come completely apart, $50 buck for the bearing and $300 for labor and it is back up and running again. :)




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