Onan Oil

[chuckconnie]

I am having trouble finding Onan 15w-40 oil for my generator. I cannot find the oil specs. For Onan oil so I could purchase a different brand. All the 15w-40 that I can find is all listed for diesel use. I do not trust it for generator use because of foaming. Maybe the Onan oil is also listed for diesel but I cannot find the answer.

Thanks. chuck

[rpfunk55]

I recently changed the oil in our Onan gas generator. Went to the local onan dealer and they sold me Valvoline, All Fleet Plus Heavy Duty Diesel Oil. Because of our location, Manitoba Canada, They recommended SAE 10W-30. I questioned the use of Oil marked "Diesel", but was assured this was the correct oil for my generator. On the back of the container it states "for turbo, diesel and gasoline engines". Hope this helps answer your question

[dickandlois]

Chuck, I have used Pennzoil and Rotella 15W-40 Diesel oil for years in both the coach diesel and the Onan generator with no issues.

I also used Pennzoil 10W-30 in my Onan Gas generators for over 15 years.

Rich.

[HarveyWhite]

Hi Chuck, you don't have a Cummins dealer near you? Every one I've been in has Onan oil.

If it's a diesel Rotella will be my pick anyway.

Harvey

[wolfe10]

I have used Rotella T 15-40 in Onan 6.3 propane generators for the last 15 years-- no problems at all.

[desertdeals69]

When we were an Onan dealer we always used 30 w Valvoline.

[kaypsmith]

http://www.cumminsonan.com/www/pdf/rv/f-1123.pdf

Here is a good reference you, page 26 and deal with correct oil for Onan generators

[kaypsmith]

Previous post should have read Page and 27, 27 has the oil ratings for both gas and diesel Onan generators.

[hermanmullins]

My opinion and my opinion only, All oils are good lubricants. I believe it is personal preference rather then which is better then the other. I have always just tried to use the same oil each time I have it changed. That way if there ever is a problem I only have one source to go to. Changing oil and filter at the correct intervals is the best thing you can do for your engine.

[kaypsmith]

Here is what Cummins/Onan has to say.

I agree with Herman, oil changes at correct intervals is utmost. And also with Brett Rotella T in almost anything is good, never thought of good diesel oil's as being foaming, only that low ash is essential for diesel use. The following is from Cummins/Onan. Hope not to break any Rules on the forum.

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.

Diesel Engine Oil Quality – Use oil meeting any of the following API

performance categories: CF, CF-4, CG-4, CH-4, CI-4 or CJ-4 where CJ-4 is

currently the highest quality available. The use of synthetic oil is not recommended.

The use of oil meeting API performance category CF-4, CG-4, CH-4 or CI-4 while

burning fuel with a sulfuric content greater than 0.5% or CJ-4 while burning fuel

with a sulfuric content greater than 0.0015% is not recommended as oil service is

negatively impacted.

Oil Viscosities – Use the following chart to select correct viscosity grades for

expected ambient temperature range.

32°

10°

0° 100°

100°

100°

-20°

-20°F

SAE-30

Viscosity Grades

15W-40

10W-30

10W-40

0 20 40 60 80 100°F

5W-30 50°

NOTE: Multi-grade oils (such as SAE 15W-40) are recommended for year-round use in Cummins Onan

liquid-cooled engines, or as a good all-season oil for air-cooled engines.

NOTE: SAE-30 is the preferred summer grade for optimum oil consumption control in Cummins Onan

air-cooled engines.

Coolant Recommendations

[jimkate]

Opinions will abound.

My propane air cooled generator does not have a block heater. When I wake up in the morning, the batteries need charging, it's cold outside, oh what the heck, I push the start button. When the Onan starts, it immediately runs at full governed speed. I expect it to start in the cold and begin to work at full capacity within a minute or two, and do it well for a couple of hours. Then I will shut it off until the next cold morning.

I use 10W30 car oil.

Jim

[Winnie2015]

On ‎10‎/‎21‎/‎2014 at 9:20 AM, kaypsmith said:

Previous post should have read Page and 27, 27 has the oil ratings for both gas and diesel Onan generators.

That website has been changed and the link no longer works

[five]

If you have a diesel coach engine and a diesel generator, sure makes it easy to use the same oil.  If it's good enough for the engine, it's certainly good enough for the generator.

[wildebill308]

20 hours ago, Winnie2015 said:

That website has been changed and the link no longer works

Welcome to the forum. Help us out, what generator do you have, Gas or Diesel? If you put your coach and other information in your signature it will help to get good answers. See my signature as an example. 

You should have a owners manual in your big bag of documentation. However as a short cut I will recommend what I have ben using with excellent results. For my diesel generator I use Shell Rotella T-6 5-40. The same oil I use in the main engine.

When I had a gas generator I used Mobil 1 15-50 full synthetic.  Now with some of the newer oil's I would run the 0-40 or the 5-50 because it flows better when cold and protects better.

Let us know what you find out.

Bill 

 

[rayin]

On 12/21/2017 at 8:12 PM, FIVE said:

If you have a diesel coach engine and a diesel generator, sure makes it easy to use the same oil.  If it's good enough for the engine, it's certainly good enough for the generator.

Yep, Cummins now recommends Valvoline Premium Blue 15W40 diesel oil.

[manholt]

Quote

Cummins now recommend Valvoline

When did this happen?  As of 2 weeks ago, their bulk oil was still Shell Rotella!

[jleamont]

6 hours ago, manholt said:

When did this happen?  As of 2 weeks ago, their bulk oil was still Shell Rotella!

Different dealers use different oils, unless a repair is under warranty, then they run with the OE recommendations. The lowest bidder scenario always comes into that decision.

As far as what oil to run in a gas powered generator, call Cummins. Our old coach had a Microlite 4000 Onan gas air cooled. Called Cummins was told 15W40 diesel oil is the recommendation. I can only assume it is the same as the OP's.

[rayin]

19 hours ago, manholt said:

When did this happen?  As of 2 weeks ago, their bulk oil was still Shell Rotella!

That is a very old service bulletin-2007. It simply means Valvoline meets/exceeds the requirements of CES 20081. Sorry, I was being flippant; any diesel oil that meets/exceeds the requirements of CES 20081/CJ-4 is approved for use in any on-road diesel or gas engine running today.

[Pickles90097]

My local Cummins dealer specifies Valvoline Premium Blue 10w30. I also have an 8k Onan generator in my boat with over 2500 hours and never a problem with Valvoline Blue.

[manholt]

Scott & Cat.  Welcome to the Forum!

Notice your 2018 coach, so as long as your covered under Warranty, then Cummins is going to use Valvoline Blue! 

Congrats on your new DP coach!

Happy and safe travels in the New Year!

[fagnaml]

For most LSU football weekends, my Onan 7500 Quiet Diesel generator runs continuously at high speed for 50 to 60 hours in 95+ F weather while running both AC units (the wife doesn't like to sweat!).  Given those rather extreme conditions, my experience in petroleum refining and lube oil manufacturing told me that conventional heavy duty engine oils (i.e. Shell Rotella 15W40) have a higher tendency to break down (lose viscosity) under extreme conditions.  Thus I decided to use a full synthetic 15W40 oil manufactured by Red Line in my generator --> https://www.redlineoil.com/15w40-diesel-motor-oil   It's not cheap at $12 per quart (vs. $7 per quart for Shell Rotella) but I think the added stability that synthetic oils provide is worth the incremental $15 cost for the three quarts required for my generator.  Royal Purple also makes a synthetic 15W40 but it is more expensive that Red Line.

[jleamont]

Mike, a good point that emphases oil sampling. I run this oil (link below) in the coach and generator, now my generator on average only gets around 100 hours per year, I pull a sample and change it every fall before it gets put away for the winter. Oil samples on the coach and generator have not shown any viscosity breakdown what so ever and the coach in 2016 ran 14,000 miles.

http://rotella.shell.com/products/t5.html

 

[manholt]

Mike, under your conditions I totally understand.  You also get the reflection off the pavement, while your sitting there.  I have no need for Red Line or royal Purple since I only run my generator (10Kw) while driving , about 6 hours a day.

I run coach between 12K to 16K a year, Rotella is fine with me!

Happy New Year.  Tell LSU to stop dropping the ball !  They had the game last night, but not when you give away a whole quarter! Geez..

[wildebill308]

I run Shell Rotella T-6 5-40 in both the generator and coach.  I get good reports on my oil samples. I only sample the coach now as I don't use the generator as much and if it breaks it won't strand me.

Bill 

[five]

Usually we run less than 10k a year. Therefore, any synthetic oil is over kill for our engine and generator.  In fact my owner's manual says to change the oil at 35k or one year, which ever comes first.  I use Rotella 15W40, and have used it on four diesels.  The beast I'm currently driving takes 42 quarts at oil change time.  Once out of warranty, I may do like I do with my Allison 4000 and have the oil sampled once year....and not change it annually.