Oil Viscosity/Ambient Temperature Relationship

[Analyzer]

Okay, here's my question for you guys. I've always been interested in how it seems that there are discrepancies between what SAE grade of oil (once the oil is up to operating temperature) and the corresponding ambient temperature in which it should operate.

For instance, comparing two Honda manuals between my Honda motorcycle/car, one states the use of a 10W30 for a cold start of 0 degrees F, with the ambient temperature up to 85F. The other manual states the use of 10W30 from 0F to 100F ambient temperature, both referencing standard petroleum oil.

I've tried researching as many graphs as I can online from reputable sources, but have found it extremely difficult to obtain reliable/conclusive temperature variants. I'd like to exclude within this discussion the use of synthetic oils with a higher Viscosity Index and limit it strictly to standard petroleum oil.

The link below by the API lists what oil to use for cold ambient temperatures: 20W** down to a 32F start, 10W** down to a 0F start, and 5W** for below 0F, but I'm curious for a petroleum oil what temperature a 5W** could safely be started, and then on the other end of the spectrum what the recommended ambient temperatures would be for the 20, 30, 40, 50 grade oil in a multi-viscosity oil.

http://www.api.org/certifications/engineoil/pubs/upload/engineoilguide_march2010.pdf

Here's an example of a graph from Car Bibles.com, but again, the ambient temperatures given vary from many others I've seen. I'm hoping to find a solid bench-mark from SAE or the API rather than trusting someones graph or opinions, and although I understand for most this topic is unnecessary/overkill, for a gear head like myself it has me interested.

https://www.google.com/search?q=oil+viscosity+ambient+temperature&source=lnms&tbm=isch&sa=X&ei=cUnLUuL5AcT6oASM84L4DA&sqi=2&ved=0CAcQ_AUoAQ&biw=1366&bih=666#facrc=_&imgrc=NPG-XyOBpC8MAM%3A%3BtrRK4pWTn2r3rM%3Bhttp%253A%252F%252Fwww.carbibles.com%252Fimages%252Fsaerates.jpg%3Bhttp%253A%252F%252Fwww.carbibles.com%252Fengineoil_bible_pg2.html%3B611%3B667


Let me know what you guys think!

 

[turtlevette]

I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.

 

[Analyzer]

Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.



I get what you're saying turtlevette, but it's not so much what the cold starting ambient temperature is that I'm interested in, but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.

 

[OVERKILL]

Originally Posted By: Analyzer
Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.



I get what you're saying turtlevette, but it's not so much what the cold starting ambient temperature is that I'm interested in, but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.


That's what the number AFTER the W means......... LOL!

 

[CATERHAM]

Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.

That's exactly right.

Even the the most advanced race oils often have a 0W rating (e.g. M1 R 0W-50) and it obviously has nothing to do with the oils ability to pump at -40 degrees. The rating is simply a byproduct of the advanced synthetic base oils hatt are used.
10W/15W/20W are basically mineral oil SAE grade prefixes that no longer have much relevance which is why most car manufactures no longer specify any oil with a cold performance rating less than 5W.

 

[Analyzer]

Originally Posted By: OVERKILL
Originally Posted By: Analyzer
Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.



I get what you're saying turtlevette, but it's not so much what the cold starting ambient temperature is that I'm interested in, but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.


That's what the number AFTER the W means......... LOL!

Perhaps I didn't explain what I'm interested in in the beginning of the topic well enough. My reply was referencing whether or not the 20 aspect in a multi-viscosity oil (like 0W20) provides proper protection in extremely hot ambient temperatures. I'm hoping to find a graph like the example I provided earlier from the API or SAE that references the viscosity of the oil and the upper limit of ambient temperatures they can operate in while providing proper protection. Does that make more sense of what I'm trying to figure out?

 

[OVERKILL]

Originally Posted By: Analyzer
Originally Posted By: OVERKILL
Originally Posted By: Analyzer
Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.



I get what you're saying turtlevette, but it's not so much what the cold starting ambient temperature is that I'm interested in, but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.


That's what the number AFTER the W means......... LOL!

Perhaps I didn't explain what I'm interested in in the beginning of the topic well enough. My reply was referencing whether or not the 20 aspect in a multi-viscosity oil (like 0W20) provides proper protection in extremely hot ambient temperatures. I'm hoping to find a graph like the example I provided earlier from the API or SAE that references the viscosity of the oil and the upper limit of ambient temperatures they can operate in while providing proper protection.


Again, that's what the number after the W means

A 10w-30 with an HTHS of 3.1cP isn't providing any more high heat protection than a 0w-30 with an HTHS of 3.1cP. In fact, if (and it does) the 0w-30 has a higher VI, if we ignore the potential for shear, the 0w-30 holds it viscosity BETTER than the 10w-30.

Now of course we can't really ignore shear. Polymer/VII's shear, but with modern base oils, lubricants sporting the 0w-xx rating are using less and less of them. Often less of them than your favourite conventional 5w-30 or 10w-30, making them actually MORE shear stable than their mineral-based cousins.

This is why M1 0w-40 is recommended for a huge array of high performance applications in all temperatures. It has excellent cold temperature performance as well as incredible high temperature performance. Quite literally the Swiss Army Knife of lubricants in applications that call for an oil with an HTHS of >=3.5cP.

 

[CATERHAM]

Originally Posted By: Analyzer
but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.

Yes a 0W-20 will provide sufficient film strength in any application with ambient temp's of 110F if the oil temp's don't get above a certain predetermined level.
Basically a 30 grade oil will allow about 10C higher oil temp's and a 40 grade oil 20C higher temp's, etc.

Now if an engine is spec'd for a 20 grade oil like a number of high performance cars are today, the manufacturer has already engineered the car to handle whatever ambient temp's and resulting oil temp's that may occur. No worries for the consumer.

 

[HTSS_TR]

Automotive manufactures test their vehicles in Death Valley in the summer, if they recommend certain oil grade it is verified that it would handle the high temperature at the Death Valley in summer. There are not many place in US hotter than Death Valley in July-September.

"The SUVs, meanwhile, pounded up and down the 5,000-foot grade from the Devil's Cornfield, an odd Death Valley landmark near Stovepipe, to the top of Townes Pass. They towed trailers weighing as much as 7,000 pounds in a brutal demonstration of their ability to handle heat and loads.

That's the secret of Death Valley, Foster says. It's not just the heat: It's the hills. Engineers pay careful attention to temperatures of transmission fluid and engine oil all the way up."

http://abcnews.go.com/Business/story?id=3559056&page=1&singlePage=true

 

[AP9]

There is always the possibility of the engine overheating.... nice to have an extra factor of safety in the event that oil temperatures should exceed what the manufacturer designed for. I'm not saying put 20W-50 in an application that calls for 5W-20, I'm talking more along the lines of--for example--sticking with 5W-30 in vehicles that originally called for it but were then back-spec'd to 5W-20.

 

[CATERHAM]

Originally Posted By: AP9
There is always the possibility of the engine overheating.... nice to have an extra factor of safety in the event that oil temperatures should exceed what the manufacturer designed for. I'm not saying put 20W-50 in an application that calls for 5W-20, I'm talking more along the lines of--for example--sticking with 5W-30 in vehicles that originally called for it but were then back-spec'd to 5W-20.

A common misconception.
Virtually all modern vehicles today have electronic safety controls to deal with dangerously high oil and coolant temp's should it happen for whatever reason.
That's why there is no lubrication advantage to running an oil any heavier than the lightest oil specified.

 

[A_Harman]

You're not going to find any "hard and fast" rules on this subject. Different engines can have different ambient temperature limits for a given viscosity rating. Your m'cycle engine is different from your car engine. Go by the ambient temperature limits in the owner's manual for the particular machine you are working on. The SAE numbers are only general guidelines.

 

[Shannow]

Originally Posted By: CATERHAM
Virtually all modern vehicles today have electronic safety controls to deal with dangerously high oil and coolant temp's should it happen for whatever reason.
That's why there is no lubrication advantage to running an oil any heavier than the lightest oil specified.


And some of the manufacturers are concerned enough that you don't even have to have a "failure" per se for these controls to kick in.

You can be using the vehicle entirely in it's performance envelope and have the nanny controls cut in...

That's underdesigned.

 

[AP9]

Originally Posted By: Shannow
Originally Posted By: CATERHAM
Virtually all modern vehicles today have electronic safety controls to deal with dangerously high oil and coolant temp's should it happen for whatever reason.
That's why there is no lubrication advantage to running an oil any heavier than the lightest oil specified.


And some of the manufacturers are concerned enough that you don't even have to have a "failure" per se for these controls to kick in.

You can be using the vehicle entirely in it's performance envelope and have the nanny controls cut in...

That's underdesigned.


Like a power derate of some sort I assume? (I've been fortunate enough to never have experienced such; only overheated once, but no damage fortunately)

 

[Shannow]

Yep, it's a design feature that if you use certain vehicles entirely within their performance envelope, and without failure of the cooling system, they cut the available power to prevent damage from overly hot (e.g.220F) engine oil...

Whereas other places, they use similar features to enable you to drive to a mechanic when a hose bursts or a system actually fails.

 

[CATERHAM]

Originally Posted By: Shannow
Originally Posted By: CATERHAM
Virtually all modern vehicles today have electronic safety controls to deal with dangerously high oil and coolant temp's should it happen for whatever reason.
That's why there is no lubrication advantage to running an oil any heavier than the lightest oil specified.


And some of the manufacturers are concerned enough that you don't even have to have a "failure" per se for these controls to kick in.

You can be using the vehicle entirely in it's performance envelope and have the nanny controls cut in...

That's underdesigned.

I don't know of any vehicle for which a 20 grade oil is specified where that occurs.
I do know of a couple of sports car models in the recent past that could drop into limp mode prematurely on a hot summer day and that's running a 30 grade or heavier oil.

Under extreme usage conditions ECU mappings are become much more sophisticated so that an engine doesn't need to drop down into a total "limp mode" if the oil and/or coolant temp's get a little high. Curtailing maximum torque at low rev's if oil gets too hot while still allowing maximum hp at higher rev's and other power adjustments is anything but "underdesigned"; quite the contrary, It is maximizing the full advantage of using a light high V.I. engine lubricant.

 

[steve20]

the above is all fine & good-if you are driving a vehicle which is 3, maybe even 4 years old. The average age of a vehicle in the US is upwards of 7 to 10 years, and many of these controls were not in place yet; for example my 04 Accord daily driver.
I think AP9 had a good idea

 

[Clevy]

Originally Posted By: Analyzer
Originally Posted By: OVERKILL
Originally Posted By: Analyzer
Originally Posted By: turtlevette
I think the philosophy is changing. There is a real argument for everyone regardless of climate to use a 0W-xx oil. The better flow at startup regardless of the temperature will provide better protection period.

I don't know why anyone would use a 10w/15w/20w oil these days.



I get what you're saying turtlevette, but it's not so much what the cold starting ambient temperature is that I'm interested in, but based off the operating temperature viscosity and the ambient temperatures they should be operated in. Given a 0W20 could be an advantageous oil, but is a 0W20 providing enough oil film strength in Palm Springs or Phoenix in the summer when it reaches upwards of 110F? That's where the API and car manufacturers have stepped in to guide you as to what grade of oil can safely be operated in various ambient temperatures while maintaining oil film strength; not thinning out, and possibly rupturing.


That's what the number AFTER the W means......... LOL!

Perhaps I didn't explain what I'm interested in in the beginning of the topic well enough. My reply was referencing whether or not the 20 aspect in a multi-viscosity oil (like 0W20) provides proper protection in extremely hot ambient temperatures. I'm hoping to find a graph like the example I provided earlier from the API or SAE that references the viscosity of the oil and the upper limit of ambient temperatures they can operate in while providing proper protection. Does that make more sense of what I'm trying to figure out?



You aren't going to find any graph or set in stone rules for a 20 grade oil. Valvetrain spring rates,max oil temps and oil temps while in steady cruise are all factors in film strength.
An oil cooler is by far the best mod that can be done to an engine to improve longevity.
If oil temps never increase to the point film strength is possibly affected and the oil film is never broken then we can infer minimal wear.
You can then benefit from using thinner oils without any fear of compromised film strength.
Today's 20 grades synthetics are tested for temps in excess of 300f and film strength is still adequate and parts are separated
The oil film thickness is irrelevant as long as the film exists. There is no gain from having an oil film thicker than what's required to maintain separation. An increase in drag is all that's achieved.
Caterham makes some very good points in his posts. Read some of his stuff. A lot of it makes sense.