Rotella oil in Onan Generator?

[dkoldman]

Originally Posted by GypsyR

Well I see that Onan is creeping out of the stone age at least a little bit.
"SAE30 replaced with 10W-30
Cummins is transitioning from SAE30 to SAE10W-30 oil blend starting Q2 2020."
It only took them....I don't know, when did 10w-30 come out? 1964?

Now if only somebody at Onan would wakey-wakey and realize that 10w-40 and 15w-40 for all intensive purposes are the exact same thing then they could update their other outdated spec and we'd have a ton of oil choices just everywhere. And this thread wouldn't exist.

I actually called Cummins Onan today. Of course I am constrained to the one person I spoke with; but he seemed very knowledgeable

1. He admitted that the various sources of information from Cummins Onan can make it confusing.
2. He says the Rotella T4 15w -40 oil I had at first would have been just fine
3. He says Diesel oils in and by itself is not an issue for Onan gasoline generators, even without a Gasoline API rating
4. He says as long as you have the right weights 15w -40, 10w -30 or Pure 30 you will be just fine.
5. He says No Synthetics Oil and was emphatic about it. I asked why? He states that the Synthetic blends leaves deposits on the cylinder wall. the cylinder block and can damage the exhaust.
6. When I told him about my choice of Chevron Delo 400 15w -40 for Diesel & Gasoline Engines for $13 / gallon; he made me verify that it was not Synthetic, when confirmed he went on to tell me how I must be the smartest & persistent RV Owner with a Cummins Onan Generator ever !!!!!

But I wasn't through

I told him about my plan to switch to a Pure 30w oil in March due to ambient temperatures going above 100F. He said Noooooo!!! He says the 15w -40 is actually better for higher temperatures than the 30w , he went on about viscosity breakdown being the reason.

So I am 100% done. I can use Chevron Delo 400 15w -40 (Non Synthetic) year around and I am very happy with no worries.

[gatorb8]

interesting, Cummins website recommends 30W for summer .....

https://shopcummins.com/products/cum...31272009826404

[Kluffinator]

Hmmm. Synthetic leaves deposits? Would that be carbon deposits that are more likely to come from conventional oil because of higher volatility? That’s one if the advantages of syn over Dino.

And if synthetic blends leave a deposit then why use Ona Max? From my research it is a synthetic blend. Does anyone here have a bottle and does the label state what it is a blend of?

https://myengineneeds.com/cummins-on...roud-rv-owner/

Something just seems off with what they told you about synthetic leaving deposits. I think I’m personally going to keep digging because I’ve never heard that about synthetic. If I can confirm that I’ll report back.

[Kluffinator]

Originally Posted by Kluffinator

Hmmm. Synthetic leaves deposits? Would that be carbon deposits that are more likely to come from conventional oil because of higher volatility? That’s one if the advantages of syn over Dino.

And if synthetic blends leave a deposit then why use Ona Max? From my research it is a synthetic blend. Does anyone here have a bottle and does the label state what it is a blend of?

https://myengineneeds.com/cummins-on...roud-rv-owner/

Something just seems off with what they told you about synthetic leaving deposits. I think I’m personally going to keep digging because I’ve never heard that about synthetic. If I can confirm that I’ll report back.

Kohler and Generac branded oils are full synthetic.

[dkoldman]

Originally Posted by Kluffinator

Hmmm. Synthetic leaves deposits? Would that be carbon deposits that are more likely to come from conventional oil because of higher volatility? That’s one if the advantages of syn over Dino.

And if synthetic blends leave a deposit then why use Ona Max? From my research it is a synthetic blend. Does anyone here have a bottle and does the label state what it is a blend of?

https://myengineneeds.com/cummins-on...roud-rv-owner/

Something just seems off with what they told you about synthetic leaving deposits. I think I’m personally going to keep digging because I’ve never heard that about synthetic. If I can confirm that I’ll report back.

This link is the 4th different Cummins Onan reference site where information is conflicted.

Two things stick out
1. They say that the OnaMax was made specifically for Diesel and NOT Gasoline
2. While they say it is Synthetic, they also stress that it is not Fully synthetic

I conclude that this is definitive proof that it matters NOT whether the oil is rated for Diesel, Gasoline or both. I can take comfort that my oil is rated for both, but I would have been fine staying with the Rotella T4

Until your link; Cummins Onan has been pretty consistent on saying Synthetics are not recommended. Your link says " Cummins Onan SAE 15W-40 is not a full synthetic engine oil. "

This link https://www.cummins.com/generators/m...-rv/onamax-oil says "Cummins does not recommend the use of Synthetic oil in Onan RV generators as there are no long-term benefits for the additional cost."

This maybe why the Onan guy admitted some issues with the documentation. He never suggested or hinted that I should buy the OnaMax rather just say the oil I had was perfect. OnaMax is not an option for me anymore.

[dkoldman]

Originally Posted by gatorb8

interesting, Cummins website recommends 30W for summer .....

https://shopcummins.com/products/cum...31272009826404

Looks like Cummins website is synonymous with the the term "internet". You can't believe everything you read on a Cummins website

Rather just go by this official thread on Onan Generator & OnaMax Oil and the single Cummins Onan Oil Expert that I have quoted verbatim as he said ; she said. But the Onan rep was very clear that for high temperatures north of 100F, the 15w 40 was the way to go.

[NXR]

Originally Posted by dkoldman

Looks like Cummins website is synonymous with the the term "internet". You can't believe everything you read on a Cummins website



Rather just go by this official thread on Onan Generator & OnaMax Oil and the single Cummins Onan Oil Expert that I have quoted verbatim as he said ; she said. But the Onan rep was very clear that for high temperatures north of 100F, the 15w 40 was the way to go.

Nice work. I failed to fully read the Delo page until after you pointed one section out but by then I had already ordered the OnaMax. I'll be out of warranty right as the last two quarts need changed anyway.

Ray

[sbleiweiss]

Originally Posted by dkoldman

5. He says No Synthetics Oil and was emphatic about it. I asked why? He states that the Synthetic blends leaves deposits on the cylinder wall. the cylinder block and can damage the exhaust.

All I can say is that my Onan 5500 runs better on synthetic blend (Rotella T5) than it did on conventional oil, and no problems have appeared after 5 years of using it and about 200 hours.

[GypsyR]

Originally Posted by Kluffinator

Something just seems off with what they told you about synthetic leaving deposits..

Tell me about it. I wonder if every vehicle manufacturer in the world is aware of this issue?

[dkoldman]

Originally Posted by GypsyR

Tell me about it. I wonder if every vehicle manufacturer in the world is aware of this issue?

Don't Cummins make most all of the engines for most all kinds vehicle, truck, tractor, heavy duty construction, caterpillar etc. manufacturers? I would think their Onan Generators would be the simplest of all of the engine they make.

I don't think I ever seen anywhere where Cummins Onan said you could not use Synthetics, they simply said it was NOT RECOMMENDED.

I think you had sarcastically interpreted that to mean they were not recommending Synthetics to save us money?

In a call with one Cummins Customer Support agent where he verified the oil of my choice (Chevron Delo 400) and the oil of choice of a number of others on this thread that were DIESEL ONLY (i.e. Rotella which was the original question), I asked why was Synthetics not recommended for the Onan Generators. I simply relayed what he said.

Sometimes the obvious may not be obvious i.e one person may be use to using a higher octane gas because of their years of experience with performance cars etc, however some of the newer engines do not perform as efficient with those higher octanes. I don't think the Mfg will say in the manual that the higher octane gas is not recommended trying to save a customer money, but because they know it is not necessary and could quite possibly cause some damage to the intricacies of the systems such as deposits, emissions etc.

With that said, and with lack documentation other than the Not Recommended we do have, it would probably take several calls to zero in with 100% certainty as to what the Cummins Corporate position is as to why it is not recommended, but it is very probable that the answer the agent provided is in fact their position. I am sure it is a question asked every day.

It is simple for me, no full synthetic blends will ever go in my new Onan 5500. I have three choices of 15w -40 I can easily buy in any Wal Mart for less than $13/gallon.

1. Chevron Delo 400
2. Super Tech
3. Rotella T4

[GypsyR]

Point #5 in post #57 says:
"5. He says No Synthetics Oil and was emphatic about it. I asked why? He states that the Synthetic blends leaves deposits on the cylinder wall. the cylinder block and can damage the exhaust."

Sarcasm? OK. Because after spending some 35 years in the automotive repair industry I call pure BS on this entire statement. I'm the type of guy that attends every career related seminar I can and reads every technical publication that comes my way. Off the top of my head I have attended at least two technical training seminars focused on engine oils. I don't claim to be the smartest guy out there but I do try and pay attention when smart people talk. The petrochemical engineers I've met and talked to have impressed me as being pretty smart. The person who gets paid to answer the phone at Onan I suspect maybe not so much.

[Phil G.]

Originally Posted by sbleiweiss

All I can say is that my Onan 5500 runs better on synthetic blend (Rotella T5) than it did on conventional oil, and no problems have appeared after 5 years of using it and about 200 hours.

Kindof the same here ... for about 14 years our gasoline Onan 4000 runs better on full synthetic (Mobil 1 EP), and it's E3 spark plug than it did when it came new from the dealer in the motorhome - and I"m farily certain that the dealer didn't deliver our new RV with those two things in it's Onan generator.

Mobil 1 EP also works great in our two Honda generators, our Lexus sedan, and our RV's V10 engine.

By the way, I don't change the oil in any engine I own based on time-in-the-crankcase. I change it based on how dirty it looks on the dipstick, and .... our Lexus has nearly 200K miles on it and one of our Honda generators is around 30 years old (an outstanding EX650, BTW).

[dkoldman]

Originally Posted by GypsyR

Point #5 in post #57 says:
"5. He says No Synthetics Oil and was emphatic about it. I asked why? He states that the Synthetic blends leaves deposits on the cylinder wall. the cylinder block and can damage the exhaust."

Sarcasm? OK. Because after spending some 35 years in the automotive repair industry I call pure BS on this entire statement. I'm the type of guy that attends every career related seminar I can and reads every technical publication that comes my way. Off the top of my head I have attended at least two technical training seminars focused on engine oils. I don't claim to be the smartest guy out there but I do try and pay attention when smart people talk. The petrochemical engineers I've met and talked to have impressed me as being pretty smart. The person who gets paid to answer the phone at Onan I suspect maybe not so much.

The Sarcasm reference is from your comment in your post #22.

"I read that as saying they believe we will be wasting our money on synthetic oil. I'm not seeing where they are actually saying not to use it. Nice of them to be so concerned about how I spend my money though. I guess."

We agree that it is what one Cummins Onan Rep said, I don't know why Cummins Onan does Not Recommend Synthetics in their Generators so I asked.

Don't forget ... It was NOT just the Cummins Onan Rep that says the Synthetics is NOT recommended. It is in all of the Cummins Onan documentation and websites. I wanted to know why Cummins Onan says it is not recommended? I had your response of "to save us money" which I assumed was sarcasm, perhaps not?

Regardless; while I had Cummins Onan on the phone confirming that my oil selection was okay, and that Diesel only oil was okay, I asked if he could explain why Cummins Onan does NOT recommend Synthetics. I simply reported what he said.

With you in the business, it seems like you may be better suited to tell us why, or find out why Cummins Onan says the Synthetics is NOT recommended. versus beating up the Onan Service Phone rep or shooting the messenger.

Remember the question is not about which oil we think is a better quality oil, rather the question is why did one of the world's largest engine manufacturers (Cummins) decide to tell all of their owners of new Onan Generators that they do not recommend synthetic oil? Until I learn something different, I have to go by what my manual says and the Onan Rep's explanation is the only logical rationale as to why I have for now. I am a consumer; so I don't have to judge or question what Cummins Onan or their Reps say. But if the Rep is wrong; that means the answer is still out there as to why Cummins Onan does NOT recommend to use Synthetics in their Onan Generators.

[dkoldman]

Originally Posted by Phil G.

Kindof the same here ... for about 14 years our gasoline Onan 4000 runs better on full synthetic (Mobil 1 EP), and it's E3 spark plug than it did when it came new from the dealer in the motorhome - and I"m farily certain that the dealer didn't deliver our new RV with those two things in it's Onan generator.

Mobil 1 EP also works great in our two Honda generators, our Lexus sedan, and our RV's V10 engine.

By the way, I don't change the oil in any engine I own based on time-in-the-crankcase. I change it based on how dirty it looks on the dipstick, and .... our Lexus has nearly 200K miles on it and one of our Honda generators is around 30 years old (an outstanding EX650, BTW).

At this junction; I think the question is why does Cummins Onan not recommend synthetic oil?

If you are a new owner ( I am ) and you read and go by manuals ( I do) it says NOT to.

FWIW, Cummins Onan does not say you can't put synthetic oil in their generators, only that it is NOT recommended. Deposits and damage to emissions is what I was told by a Onan Rep as to why.