Recomended oil for Onan 4KW generator

[nadsab]

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.

[IAMICHABOD]

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.

[nadsab]

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...

[IAMICHABOD]

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.

[tpi]

No oil filter on my Onan 4000

[nadsab]

Thanks. What about the oil filter?

[tpi]

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.

[nadsab]

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

[IAMICHABOD]

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.

[nadsab]

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?

[jaycocreek]

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.

[Old_Crows]

What ericsmith32 said in post #5.

15W40 is probably the hot tip if you are going to be using the generator underway due to the increased temperatures under & around the RV.

While you can use a diesel 15W40, I'd suggest getting the real deal by Onan. Or an oil engineered for aircooled motors. Aircooled engines require a different additive package than diesels. Change the oil by the Onan schedule.

[jaycocreek]

I used to buy nothing but Onamax which then was 15-40..I bought it by the case and have some left over but it is so old that I decided not to use it so I took the bottle down to the parts store and matched the services and got 10-30 which I think Onan is recommending now.

[tpi]

rjstractor wrote:

tpi wrote:
Onan manuals are always an interesting read. There is an Onan standby generator using our Ford V10. 15W40 oil is recommended, and 5W30 is only recommended to 50 degrees F. FWIW they also call for cylinder head rebuild at 1000 hours (or two years whatever first) on the V10. 1000 hrs. translate to 30,000 40,000 miles of typical driving? Ummm don't think I'll be pulling the heads..

A stationary generator application is a completely different duty cycle than a vehicle, so I wouldn't think you could even translate hours to miles driven. It would be interesting to see how many hours the V10 would run in a generator application.

It would be.. Of course the generator applications could be as variable as miles driven. Generator doing a lot of 80-100%. Or mostly 30-50%. Or short test runups. Generator at hot standby, or not. Still when airport shuttle V10s have gone over 500,000 miles (think of the hours here) and they pull heavy motorhomes along for 160,000 miles or more I would question whether a cylinder head would be worn out at 2 years/1000 hrs whichever occurs first. Especially if compression and oil consumption measured good. These engines in generator duty are running 1800 RPM, turbocharged, and putting out about 170 HP maximum-conditions which may or may not be harder on certain parts of the engine vs. automotive applications.

[IAMICHABOD]

15W 40 Also,mainly because when I need to use it to run A/C the outside temp in the desert is very high.

It is also what Onan recommends for this application.