Another thick/thin article to discuss

[fdcg27]

You got the right answer but your reasoning is flawed.
A thicker grade will experience more heating going through the main bearings due to internal friction than will a thinner grade, so higher oil temperatures are the result.
This partly offsets the thicker oil film that a thicker grade can provide, since viscosity is temperature dependent.

 

[ZeeOSix]

Originally Posted By: JLTD
Originally Posted By: article
Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.


Also backs up what BITOG already knew: filtration is important.


Lots of guys in the oil filter forum don't think a filter's efficiency makes any difference ... even though there are controlled field tests with data that show otherwise.

 

[ZeeOSix]

Originally Posted By: article
Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.

In other words, an SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F. This approximation works well in the 190°F to 260°F temperature range. One might be surprised at the slight amount of difference between straight viscosity vs. multiviscosity oils with the same back number (for example, SAE 30, SAE 5W-30, and SAE 10W-30).

If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture.


That right there is exactly why a thicker oil should be used in anything that is pushed above more than just beguine street use. Heat causes oil to thin down and decreases MOFT, which makes it easier for have metal-to-metal contact and wear to occur. Thicker oil will also have a higher HTHS value, which is critical if the oil heats up well above the normal 200~220 deg F that street driving will result in.

And running a grade higher (5W30 instead of 5W20) even if for just normal street driving isn't going to hurt anything but a nano-MPG less gas mileage, and it will ensure added engine protection in case oil temperatures do rise above normal for some reason.

 

[fdcg27]

The thing is that running a thicker grade will always and everywhere result in higher oil temperatures than will a thinner grade, so one cannot focus on kinematic viscosity alone.
A better approach might be to focus on HTHS, which is not directly related to kinematic viscosity.
A 10W-30 grade oil will have a fairly tight range of kinematic viscosities but does also have a fairly large range of HTHS viscosities across the various products offered, just as an example.

 

[demarpaint]

Originally Posted By: ZeeOSix
Originally Posted By: article
Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.

In other words, an SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F. This approximation works well in the 190°F to 260°F temperature range. One might be surprised at the slight amount of difference between straight viscosity vs. multiviscosity oils with the same back number (for example, SAE 30, SAE 5W-30, and SAE 10W-30).

If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture.


That right there is exactly why a thicker oil should be used in anything that is pushed above more than just beguine street use. Heat causes oil to thin down and decreases MOFT, which makes it easier for have metal-to-metal contact and wear to occur. Thicker oil will also have a higher HTHS value, which is critical if the oil heats up well above the normal 200~220 deg F that street driving will result in.

And running a grade higher (5W30 instead of 5W20) even if for just normal street driving isn't going to hurt anything but a nano-MPG less gas mileage, and it will ensure added engine protection in case oil temperatures do rise above normal for some reason.

I'll take the nano-MPG less, and run with the 30 grade.

 

[Zee09]

Originally Posted By: JAG
I largely agree with the points made in the article. Most people here don’t seem to have a solid understanding of tribology, which I find strange given that this is a motor oil forum. So, much talk is about anecdotes, personal experiences, myth propagation, and believing advertising. I generally don’t get involved in threads full of such discussions due to lack of interest.


I prefer anecdotal gibberish over long winded nonsensical theories.

 

[ZeeOSix]

Originally Posted By: HammerHead0313
This has been a topic I've been over many times and have tested in my old 2013 Ram 5.7 while canyon racing in north Georgia. One thing I want to bring up is, internal engine components are cooled by oil Directly and cooled by coolant Indirectly. I switched from Dodge Ram recommended 5w20 to a 5w30 engine oil and my oil sump temperatures were 16 degrees Fahrenheit Hotter than the 5w20. Why? Because thinner oils flow better through internal engine components, and pull more heat from your engine. The thicker oil flowed slower through the internal engine components and drove the oil temps up.


As fdcg27 already mentioned, the extra heat is the thicker oil producing more shear drag in the journal bearings which causes the oil to heat up more as it's squeezed through the journal bearings. As far as oil moving through the engine where it's pressurized by the oil pump, the flow rate will basically remain the same due to the positive displacement oil pump.

Originally Posted By: HammerHead0313
Please see bearing to journal clearance standard for the 4th gen Hemi with the 5.7

No 1) .0015-.003
No 2) .0019-.0035
No 3) .0015-.003
No 4) .0019-.0035
No 5) .0015-.003


I think a lot of engines specified for oils heavier than 5W20 use similar bearing clearances. Those are pretty standard clearances for most modern engines made over the last 20+ years. It's pretty obvious that oils aren't really specified solely on the journal bearing clearances, as manuafacturer's like Ford, etc will say use 5W20 on the street and then use 5W50 on the race track in the same engine.

 

[ZeeOSix]

Originally Posted By: fdcg27
The thing is that running a thicker grade will always and everywhere result in higher oil temperatures than will a thinner grade, so one cannot focus on kinematic viscosity alone.
A better approach might be to focus on HTHS, which is not directly related to kinematic viscosity.
A 10W-30 grade oil will have a fairly tight range of kinematic viscosities but does also have a fairly large range of HTHS viscosities across the various products offered, just as an example.


What I was getting at was more long the lines that in most cases a 5W30 will have a higher HTHS than a 5W20. The only way that might not be true is if a 5W20 was on the very high end of the 20 range and a 5W30 was on the very low end of the 30 range, and the 20 had a better HTHS property due to specific formulation.

But in most cases if you compare the oil specs (if the manufacturer does give HTHS, they don't always), a 5W30 will have a higher HTHS than a 5W20. I highly doubt you'll find a 5W20 in the middle of the 20 range spec that has a higher HTHS than a 5W30 in the middle of the 30 range spec.

 

[fdcg27]

Okay, but you can easily find 10W-30s that have 3.5 HTHS and that was my point.
Many of those who think that they're looking for a thicker oil might really be looking for a higher HTHS oil.
As you are well aware, there are different ways of measuring viscosity and folks might be well advised to focus on those that actually matter in reducing wear.

 

[Bryanccfshr]

Originally Posted By: fdcg27
Okay, but you can easily find 10W-30s that have 3.5 HTHS and that was my point.
Many of those who think that they're looking for a thicker oil might really be looking for a higher HTHS oil.
As you are well aware, there are different ways of measuring viscosity and folks might be well advised to focus on those that actually matter in reducing wear.


I agree with that. I seek oils with 3.1-3.6 hths for my purposes

 

[Shannow]

Originally Posted By: fdcg27
Okay, but you can easily find 10W-30s that have 3.5 HTHS and that was my point.
Many of those who think that they're looking for a thicker oil might really be looking for a higher HTHS oil.
As you are well aware, there are different ways of measuring viscosity and folks might be well advised to focus on those that actually matter in reducing wear.


That's why oils should be graded "xW-HTHS"...since the discovery of non Newtonian behaviour in polymer thickened oils in the 80s, HTHS has been the metric that counts.

 

[hatt]

Originally Posted By: Snagglefoot
Ford has been specifying 5w20 for 15 years. Get over it. But thanks for posting.
That's not a shining example since Ford has went back to 5w-30 for the 6.2. And allows 5w-30 in the 6.8.

 

[fdcg27]

Originally Posted By: Shannow
Originally Posted By: fdcg27
Okay, but you can easily find 10W-30s that have 3.5 HTHS and that was my point.
Many of those who think that they're looking for a thicker oil might really be looking for a higher HTHS oil.
As you are well aware, there are different ways of measuring viscosity and folks might be well advised to focus on those that actually matter in reducing wear.


That's why oils should be graded "xW-HTHS"...since the discovery of non Newtonian behaviour in polymer thickened oils in the 80s, HTHS has been the metric that counts.


You have plenty of folks here who demonstrate a lack of understanding of what the SAE grades really indicate.
Imagine the confusion among the DIY and even service shop masses were oils to be graded as you suggest, even though this would actually be a more useful system.
OTOH, you also have those who fail to recognize that there is a tradeoff between wear and fuel economy. Since no passenger vehicle in which any engine is installed is designed and built to last indefinitely, there may be no benefit in seeking lower wear levels than those provided by whatever oil grade the manufacturer recommended for the market in which the vehicle is operated.
I have yet to see a used car offered for sale with the ad copy noting that the engine had seen only HTHS 3.5 oil throughout its life.

 

[Shannow]

Originally Posted By: fdcg27
I have yet to see a used car offered for sale with the ad copy noting that the engine had seen only HTHS 3.5 oil throughout its life.


I sold my 2003 Navara last year on out version of craigslist, with the names, weights, and installation dates of all of the drivetrain lubes, plus a precis of the engine oils that had been through it and the current fill.

Guy turned up with cash and didn't haggle.

 

[jakewells]

Oil weight doesn't effect the fuel economy of what i drive my old relics could care less.

 

[Shannow]

Originally Posted By: fdcg27
You have plenty of folks here who demonstrate a lack of understanding of what the SAE grades really indicate.
Imagine the confusion among the DIY and even service shop masses were oils to be graded as you suggest, even though this would actually be a more useful system.


They already don't get the difference between engine oil grades and gear oil grades.

And J300 had HTHS included when it was discovered, and while the KV100 numbers haven't moved (bar the 20 and belows), the HTHS grades have been evolving.

Which is stupid, as monogrades, on which J300 was created were Newtonian, which no temporary shear at high shear rates...then multigrades were invented, then "grades" not protecting like they should became a problem, the exploration, then HTHS, then the inclusion of HTHS minimums in J300...then changing them as polymers become better.


What is now HTHS was ALWAYS the answer, just the industry were reliant on the wrong metric and got caught out.


Stick to 20, 30, 40 then for simplicity and to not confuse the masses...just drop the KV100 requirement, and make the grade reliant on the minimum HTHS.

Then you'd lose the Unicorns like the Japanese 0W20s, and M1 0W50 racing that use KV100 to get the "grade", while chasing HTHS minimums.

 

[Shannow]

Originally Posted By: fdcg27
OTOH, you also have those who fail to recognize that there is a tradeoff between wear and fuel economy. Since no passenger vehicle in which any engine is installed is designed and built to last indefinitely, there may be no benefit in seeking lower wear levels than those provided by whatever oil grade the manufacturer recommended for the market in which the vehicle is operated.


I've always said that if the engine outlasts the chassis, and the user saves a few bucks in gasoline, that it's senseless sending it to the boneyard with 20,000 miles or 50,000 miles left on the engines.

Problem is that most of the BIOTG "thin crowd" feel that their masculinity is being questioned if the OEMS (and worse, CAFE), made that decision for them.

That's when the "pile of failed engines" strawman comes out.

 

[jakewells]

Originally Posted By: ZeeOSix
Originally Posted By: JLTD
Originally Posted By: article
Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.


Also backs up what BITOG already knew: filtration is important.


Lots of guys in the oil filter forum don't think a filter's efficiency makes any difference ... even though there are controlled field tests with data that show otherwise.

How good is the fram tough guard on that test?

 

[fdcg27]

Is there really such a thing as a true monograde?
Even absent VIIs, all basestocks have some inherent VI.
Therefore, is an SAE 30 really a monograde, or is it really something like a 25W-30?
Or are we defining monogrades as those oils which contain no VIIs and are therefore not subject to temporary shear?

 

[webfors]

Originally Posted By: ZeeOSix
Originally Posted By: article
Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.

In other words, an SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F. This approximation works well in the 190°F to 260°F temperature range. One might be surprised at the slight amount of difference between straight viscosity vs. multiviscosity oils with the same back number (for example, SAE 30, SAE 5W-30, and SAE 10W-30).

If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture.


That right there is exactly why a thicker oil should be used in anything that is pushed above more than just beguine street use. Heat causes oil to thin down and decreases MOFT, which makes it easier for have metal-to-metal contact and wear to occur. Thicker oil will also have a higher HTHS value, which is critical if the oil heats up well above the normal 200~220 deg F that street driving will result in.

And running a grade higher (5W30 instead of 5W20) even if for just normal street driving isn't going to hurt anything but a nano-MPG less gas mileage, and it will ensure added engine protection in case oil temperatures do rise above normal for some reason.


Some use cases will have different viscosity requirements. Example, my towing through Cape Breton last summer:

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4486979/PP_-_Mix_5w30_&_0w40?#Post4486979