What temperature is too hot for conventional oil?

[CarbonSteel]

And here is Mobil's response:


From: Leblanc, Luc R [mailto:[email protected]] On Behalf Of TSC Americas /SM
Sent: Tuesday, June 21, 2016 14:33
To:
Subject: RE: Lubricants: Technical Question (LRL)

Hello 2015_PSD,

I think you can appreciate the fact this is not an exact science, and many factors contribute to oil life. Lubricants don’t begin to breakdown at set temperatures, but their degradation accelerates at different rates.

The condition of the oil (presence of water, wear metals, previous oxidation) when it is exposed to those elevated temperatures will have an effect on thermal breakdown. So “max temperature” for an oil is a moving target, and educated guesswork.

With all that being said, as far as rules of thumb go, premium minerals @ 240-250°F, and synthetics @ 280-300°F typically deliver an acceptable service life. But that is simply from an oil life/condition standpoint – one needs to consider if the oils keep adequate viscosity for proper lubrication and protection at those elevated temps. No concerns if Ford considers your 249°F as normal, but seeing much higher than 260°F would likely signal a problem has occurred or is imminent.


I’ll leave you with this image below of mineral vs synthetic. I know which one I would want in my engine.

Best regards,

Luc LeBlanc
Americas Technical Help Desk
ExxonMobil Products Technology

ExxonMobil Business Support Centre Canada ULC
Email: [email protected]
US: 1.800.662.4525 (Fax: 1.262.313.2316)
Canada: 1.800.268.3183



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From:
Sent: Tuesday, June 21, 2016 2:13 PM
To: TSC Americas /SM
Subject: Lubricants: Technical Question (LRL)

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Question:
Can you tell me what the maximum operating temperature would be for the oils listed below? I realize there is a flashpoint temperature on the PDS, but I am wondering how hot the oil can be before it begins to breakdown and lose effectiveness/cause varnish and sludge. Case in point, I had some sustained oil temperatures in my Ford F-250 Powerstroke 6.7L that were 230°F to 249°F with ambient air temperatures of 115°F. Had I been towing, I am going to assume, I would see temperatures in the 260°F range. I am attempting to make a decision between synthetic and conventional oil for this application/operating conditions and would appreciate your advice.

Oil #1 – Mobil Delvac 1 ESP 5W-40 full synthetic
Oil #2 – Mobil Delvac 1300 15W-40 conventional

Thanks in advance for your help and advice.

 

[dustyroads]

I think very highly of Delo products but wow...why do they even bother to reply? Why do they even accept email inquiries if they can't take more than ten seconds to reply?

While I still believe conventional oils have proven to be more than adequate (at least in HDEO form) in high temp operation, I would continue to follow Ford's recommendation of using 5W40 for the situations you experienced in the desert southwest. I can't blame anyone for that.

Thanks to 2015_PSD for your efforts in communicating with the oil companies!

 

[CarbonSteel]

Originally Posted By: dustyroads
I think very highly of Delo products but wow...why do they even bother to reply? Why do they even accept email inquiries if they can't take more than ten seconds to reply?
I was surprised by that as well--totally non-committal. No worries on the communication. I wanted to have some insight about it and I learned what company recommends (more or less). FWIW - Kendall, Shell, and Mobil answered within hours and Chevron took 1 day. All of them were fairly fast with the responses.

 

[Garak]

Originally Posted By: userfriendly
Garak; You agreed with Kendall's letter. Which synthetic vs my dino?

I didn't say I agreed with Kendall's letter as gospel about every manufacturer's oils under all conditions and in all perpetuity. I'm satisfied that Kendall is speaking specifically about their product line and are in some sort of position to do so.

 

[Garak]

There's more on oxidation here and here. As for oxidation rates doubling for every 10 Celsius and my comment that I've heard that before, well, I better have heard that before, since as the one article notes, it's a generalization of an common Arrhenius plot.

Also, check the ACEA sequences here. E7, E9 address oxidation. Considering the lubes you've chosen so far, 2015_PSD, have been E7, E9 lubricants, you've at least got something. There are conventional, blend, and synthetic E7, E9 lubricants, too.

It just goes to show that if you choose a lube with the correct specifications, certifications, and builder approvals, your very likely not to make a mess of things.

 

[userfriendly]

In addition to the above links Garak posted, oxygen must be present for oxidation to occur.

 

[CarbonSteel]

Originally Posted By: userfriendly
In addition to the above links Garak posted, oxygen must be present for oxidation to occur.
Is not there? I was not under the impression that a crankcase is sealed from the atmosphere.

 

[kschachn]

Well even if it is, the atmosphere isn't the only source of oxygen.

 

[CarbonSteel]

Originally Posted By: Garak
There's more on oxidation here and here. As for oxidation rates doubling for every 10 Celsius and my comment that I've heard that before, well, I better have heard that before, since as the one article notes, it's a generalization of an common Arrhenius plot. Also, check the ACEA sequences here. E7, E9 address oxidation. Considering the lubes you've chosen so far, 2015_PSD, have been E7, E9 lubricants, you've at least got something. There are conventional, blend, and synthetic E7, E9 lubricants, too. It just goes to show that if you choose a lube with the correct specifications, certifications, and builder approvals, your very likely not to make a mess of things.
Thanks Garak. For operating conditions that I experienced, I am totally confident in the oil choice that I made and it seems (generally) the oil companies recommend the same as does Ford. Under less severe conditions, I would not have a problem using a conventional, but 249°F bulk temperature (for me) is too hot for a conventional. It could be fine for others, but I would rather not test the MTBF rate on any of the engine components in my new truck--in particular the turbo bearings.

 

[kschachn]

I would think that since the rule of thumb is that the rate of a chemical reaction doubles for every 10 degrees, then it is dependent on the rate of the reaction to begin with. Plus, aren't there oxidation inhibitors in motor oil?

 

[Jetronic]

the easiest way to tell is to monitor the TBN...

 

[Pontual]

Originally Posted By: Pontual
160F is 71C, the moisture isn't get boiled off (but makes a slow vaporization) and the oils are starting to slowly oxidise even though it would take ages to get out of service spec, from oxidation thickening. Now, at 170F the oxidation doubles, at 180 quadruples, at 190 octuples, 200F is 16 times more than @ 160, at 210F it is 32 times quicker than at 160F, 220 is 64 times, 230F is 128 times and 240F gives 256 times quicker, finally at 250F you get 512 times quicker compared to the same oil at 160F, having a few hours time of engine oil life. Run it at water boiling point max, or you're shortening oil life giving that pretty oci of 5k miles or even less. Racing engines, cut oil life a lot. Now I'm talking of bulk oil temp,not instantaneius raise at ring pack, bearings and valve guides stem, or shut down soaking. That's another animal.


Oil Each 10F doubles oxidation rate, in pg.

 

[kschachn]

Doubling the reaction rate does not necessarily double the oxidation rate, especially if there are oxidation inhibitors in the oil.

Jetronic's suggestion is a good one.

 

[CarbonSteel]

Originally Posted By: kschachn
Doubling the reaction rate does not necessarily double the oxidation rate, especially if there are oxidation inhibitors in the oil.
According to one of the oil companies that I contacted it does--even with the oxidation inhibitors in the oil.

 

[roadrunner1]

Originally Posted By: Garak
There's more on oxidation here and here. As for oxidation rates doubling for every 10 Celsius and my comment that I've heard that before, well, I better have heard that before, since as the one article notes, it's a generalization of an common Arrhenius plot.

Also, check the ACEA sequences here. E7, E9 address oxidation. Considering the lubes you've chosen so far, 2015_PSD, have been E7, E9 lubricants, you've at least got something. There are conventional, blend, and synthetic E7, E9 lubricants, too.

It just goes to show that if you choose a lube with the correct specifications, certifications, and builder approvals, your very likely not to make a mess of things.


The Deere Plus 50 II 10w-30 I use in my PowerStroke is CJ-4, and also E7, E9. Its marketed as an extended drain lube and its a conventional. This was the contention of my contributions to this thread and with all of the information provided within this topic I still stand by my remarks.

A synthetic isn't needed for superior engine protection, and until someone provides UOA information otherwise its all conjecture. Most HDEO's meet and or exceed current specs, either or both API & European, this spec was designed to handle the temps seen with modern high speed 4 stroke diesel engines with exhaust after treatment systems. The increased temps seen are a direct result of EPA mandated emissions systems. I have yet to see a sub-par UOA posted here from an oil not able to handle the higher temps of a modern diesel, synthetic or conventional.

 

[kschachn]

Originally Posted By: 2015_PSD
Originally Posted By: kschachn
Doubling the reaction rate does not necessarily double the oxidation rate, especially if there are oxidation inhibitors in the oil.
According to one of the oil companies that I contacted it does--even with the oxidation inhibitors in the oil.


Yeah, I fell into my own trap about the use of the word rate. Your post and Pontual's are correct.

I should have said the amount of overall oxidation, rather than rate. My mistake.

 

[Pontual]

Yes, you're more righter than I am. I misplaced the units as the rate doubles at each 10 Celsius and not at each 10 degrees Fahrenheiht as I posted in error. So the numbers are others ... bad day. Yuo get 160F and doubles at 178F and increments of 18F, not 10Fs...

 

[CarbonSteel]

Originally Posted By: roadrunner1
A synthetic isn't needed for superior engine protection, and until someone provides UOA information otherwise its all conjecture. Most HDEO's meet and or exceed current specs, either or both API & European, this spec was designed to handle the temps seen with modern high speed 4 stroke diesel engines with exhaust after treatment systems. The increased temps seen are a direct result of EPA mandated emissions systems.
Except, it would seem that Ford, Kendall, Mobil, and Shell disagree with a conventional oil handling the temperatures I experienced. To each his or her own and I realize you are doing what works for you, but I prefer to err on the side of caution.

 

[Garak]

I'd put it this way. Roadrunner1 certainly isn't wrong. But, the argument can be made that the synthetic would hold up for longer. Doug Hillary didn't switch to synthetics because he likes the cost of synthetic oils down under. Now, if it were the original 3,000 mile OCI on the original Powerstroke, I'd keel over after filling that with synthetic.

 

[Doug Hillary]

Hi,

Originally Posted By: Garak
I'd put it this way. Roadrunner1 certainly isn't wrong. But, the argument can be made that the synthetic would hold up for longer. Doug Hillary didn't switch to synthetics because he likes the cost of synthetic oils down under. Now, if it were the original 3,000 mile OCI on the original Powerstroke, I'd keel over after filling that with synthetic.

Garak - you are correct. It was a commercial decision based on testing Mineral, Semi-synthetic and a full synthetic. Testing was to determine the condition of the lubricant and it was conducted over many OCIs and hundreds of 000s of OTR kms
Condemnation limits were reached as follows;

Mineral lubricant = 20kkms
Semi-synth = 35kkms
Synth = 90kkms

UOAs were used over many many millions of kms to confirm OCIs based on establish lubricant condemnation limits established via the OEM and the lubricant supplier

I presented the pictures of my engine teardown results (on engine at 1.2m kms) at the BITOG Conference held in Chicago several years ago

Of course I've been involved with the UOAs for several decades and in lubricant field testing for several Oil Companies since around 1959