Recomended oil for Onan 4KW generator

I do mine at one year or 100 hrs,per Onan specs. That is what I have records for on my Ex Rental,900 + hours and going strong and no problems at all.

OK great thanks just changed the oil. How many gen hours are recommended between oil/air filter changes?

Sorry about the dumb questions we can't find our manual...

As long as you are doing the oil the only filter you need to worry about on the 4000 is the Air Filter, Change mine with every oil change.

No oil filter on my Onan 4000

Thanks. What about the oil filter?

Mine holds 1.6 quart. There's a small removable panel on the bottom of the sheet metal housing held by a couple of screws (facing the ground) Remove that and you see the drain plug.

Where is the drain plug? Does it hold more than one quart?

nadsab wrote:
So I just use a funnel and fill the oil using the port where I check the oil level?

Also - should I completely change the oil? Drain and refill?

Yes, on both and using one of these makes it much easier.

So I just use a funnel and fill the oil using the port where I check the oil level?

Also - should I completely change the oil? Drain and refill?

nadsab wrote:
Hi

We have an Onan model 4KYFA26100K 4 KW generator in our Class C and were wondering what is the recommended oil type for it?

Thanks.

This is straight from Onan...

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.

As far as the weights go,we all have different needs in the different regions we live and use the generator in.

The most common issue with Onan generators is lack of use and old gas..Again from Onan:

NOTE: Fill up with fresh gas! The single most common service issue is stale or
contaminated fuel. Always use fresh gas! The gas should not be more than 30
days old. Fuel stabilizer extends the life of your fuel. Stale fuel clean-out is not
covered under your warranty.