If thick oil offers more protection, then isn't cold oil best?

[Foxtrot08]

No, Boyle's Law doesn't apply to liquids. Go read up about it ... you said "If you want to argue with physics, I’m the wrong person." Doesn't see to be the case if your stating the wrong physic law.

Oil is only compressible to a very small degree under very high pressures - see below. The high pressure wedge is created in a journal bearing due to its rotation and can therefore support many thousands of pounds on a small area, like a piston rod after combustion. But that doesn't relate in any way to your claim of "it comes down to Volume vs Pressure". I explained how an oiling system works and the simple relationship between oil pressure and oil volume when fed by a PD oil pump. In and ICE force fed oiling system, pressure and volume are directly related ... can't have one without the other.

View attachment 262672


Boyle's Law has nothing to do with an engine oiling system, unless you want to try and run air for a "lubricant".


Sure, and basically what I've already said. But the part you don't really seem to understand is that proper lubrication is dependant on supplying an adequate oil volume to the parts. It takes pressure on the oil at the pump to be able to supply that volume throughout the oiling system. The pressure between moving parts due to the oil pressure really doesn't add much if anything to the function of lubrication, including journal bearings. There were actually old ICE that simply fed the journal bearings oil simply under the force of gravity - no oill pump at all. @OVERKILL posted up some info on that in another thread discussing lubrication and journal bearings. Maybe he can pop in and share that again here.


I cited the Wikipedia page on Boyle's Law because you didn't really know what "law" it was.


Doesn't matter what "law" you think it behaves as, the fact of fluid dynamics is that on a fixed flow resistance system, you need more pressure to push more volume through the resistance (ie, engine oiling system) if the viscosity is held constant. And if you held the engine RPM constant to keep the pump output volume constant, the pressure would also go up as the viscosity increased. Every engine oiling system behaves in this basic manner.

I know exactly what I was saying. Because I, actually just told you what you should have been citing. So your gaslighting can stop now. I do know exactly what I was saying. I cited it, as I said, because most people recognize Pv=K. It’s an extremely simplified way to look at it. But how else do you reply back in one sentence.

Everything you just assumed, in the last part, is corrected by a Reynolds’s number.

So no, not everything behaves in that manner. Because you’re assuming linear flow. When it’s a turbulent flow. So pressure isn’t going to directly increase because your reynolds number changes. Thus, if I remember right, Re = ρ u dh / μ.

But none of this applies to OP’s question. OP’s question was hot vs cold oil. Which, engineering wise still goes back to pressure vs volume.

Next, Viscosity is independent of pressure. Until it reaches critical pressures. Which, will make it a solid. As I covered.

Which, in your situation you just cited, in physics is called the Transport Phenomena, is a… shocker. An ideal gas theory. Kinda, you know, like Boyles law. So… are you saying I’m right in saying, at the 38,000 foot view, that the engineering concept I mentioned, is right? Pressure vs volume?

Viscosity in your situation, is decreasing because of physics. As you move a fluid, you’re going to create heat. Unless you’re saying the engine is operating under a vacuum or is some how super cooled. So as you operate your engine at a constant RPM, you’re going to generate heat. This heat is going to decrease viscosity out of the oil pump. Your pressure, is going to decrease. Thus, pressure vs volume.

Edit: Fourier's law. That’s what I was trying to remember. Sorry. I’m also really drunk right now. And it’s been a long time since any practical thermodynamics classes for me. I’m a bad engineer.

 

[4WD]

Yes it’s a gas law used often in my job …
Oil is only slightly compressible (also something our engineers calculate)
Hydraulics are hydraulics (yes, work stuff too) Newtonian, shear stress, KV, etc … but oil pressure is dynamic hydraulics as said already - where viscosity often is overstated here on this site … (one of the lowest impacts on residual pressure - hot, not talking last month in International Falls)
Flow rate and conduit fluid area are big ones.
@Shannow on what’s different inside a journal bearing that’s getting feed from leakage in/out … a good analogy of the separation force is a skim board in shallow water …

 

[cheesepuffs2]

Viscosity in your situation, is decreasing because of physics. As you move a fluid, you’re going to create heat. Unless you’re saying the engine is operating under a vacuum or is some how super cooled. So as you operate your engine at a constant RPM, you’re going to generate heat. This heat is going to decrease viscosity out of the oil pump. Your pressure, is going to decrease. Thus, pressure vs volume.

I had the same takeaway when reading that example. Not sure how that example makes sense.

Pressure vs volume really was the basis of my original post, you nailed it. To those who may have missed the point, I'm not literally suggesting that cold oil is superior to operating temperature oil. My point is essentially that, if we were to run overly thick oil, on the notion that "thicker oil provides more cushion between parts, and more cushion is always best for an engine", well, can we really make that statement? Foxtrot's example of the 3" gear driving very thick oil both when cold and then when preheated matches the spirit of my original post very well. That's exactly what I'm talking about.

 

[ZeeOSix]

I know exactly what I was saying. Because I, actually just told you what you should have been citing. So your gaslighting can stop now. I do know exactly what I was saying. I cited it, as I said, because most people recognize Pv=K. It’s an extremely simplified way to look at it. But how else do you reply back in one sentence.

No you didn't know what you were saying ... and you don't really know what you're even saying when you claim it's "pressure vs volume".

Everything you just assumed, in the last part, is corrected by a Reynolds’s number.

So no, not everything behaves in that manner. Because you’re assuming linear flow. When it’s a turbulent flow. So pressure isn’t going to directly increase because your reynolds number changes. Thus, if I remember right, Re = ρ u dh / μ.

I simply described how an engine oiling system works. It's really quite simple for anyone who understands basic fluid dynamics.

But none of this applies to OP’s question. OP’s question was hot vs cold oil. Which, engineering wise still goes back to pressure vs volume.

Deflection tactic. You're the guy who brought up "pressure vs volume".

Next, Viscosity is independent of pressure. Until it reaches critical pressures. Which, will make it a solid. As I covered.

A billion miles from ever happening in an engine. So what's the point? Just more deflection from the actual focus of the discussion.

Which, in your situation you just cited, in physics is called the Transport Phenomena, is a… shocker. An ideal gas theory. Kinda, you know, like Boyles law. So… are you saying I’m right in saying, at the 38,000 foot view, that the engineering concept I mentioned, is right? Pressure vs volume?

Nothing in an engine oiling system is related to an "ideal gas theory". So you are still way off base, even at a 38K foot view. "Pressure vs volume" isn't a "verses" ... they behave in harmony together. If you want more volume you need more pressure, all other factors being constant. It's simple fluid dynamics. Same princoiple applies to water flowing in your plumbing, or water flowing through a garden hose.

Viscosity in your situation, is decreasing because of physics. As you move a fluid, you’re going to create heat. Unless you’re saying the engine is operating under a vacuum or is some how super cooled. So as you operate your engine at a constant RPM, you’re going to generate heat. This heat is going to decrease viscosity out of the oil pump. Your pressure, is going to decrease. Thus, pressure vs volume.

Anyone should know that heating up oil is going to decrease the viscosity ... so what. I'm talking about steady-state conditions. Fact is, and always will be that in an oiling system if you want more flow volume you need more pressure, viscosity held constant of course. If the viscosity decreased because of heat that the volume is constant, then the pressure decreases ... but since the volume is constant the part are still getting adequate lubrication. The pressure can be anyplace on the spectrum as long as the flow volume is adequate to lubricate the engine

 

[ZeeOSix]

I had the same takeaway when reading that example. Not sure how that example makes sense.

Pressure vs volume really was the basis of my original post, you nailed it. To those who may have missed the point, I'm not literally suggesting that cold oil is superior to operating temperature oil. My point is essentially that, if we were to run overly thick oil, on the notion that "thicker oil provides more cushion between parts, and more cushion is always best for an engine", well, can we really make that statement? Foxtrot's example of the 3" gear driving very thick oil both when cold and then when preheated matches the spirit of my original post very well. That's exactly what I'm talking about.

I just read the first post, and there was nothing there to say or imply that it was asking or talking about "pressure vs volume". It was simply asking about how more viscosity can be beneficial or not in terms of engine protection. He didn't nail anything with the "pressure vs volume" .. claiming one is better than the other, or whatever "verses" between them is suppose to mean.

 

[Joba27n]

I'm extremely sceptical of that story, as the 40 wt, like any other oil thickens significantly when temperature drops and would cause the same issues eventually. In fact there's not likely more than 20°F difference before both oils are the same viscosity. I don't know where he lives, but for me that's the difference between starting during day time or night time....

Now if he put 20W50 in and ran the engine below 0°F, i can see that happening..... but then it would also happen using a 20W-40.

Im not Savvy enough to tag everyone in response but I agree with the counter arguments you guys have all made and also compare bearing specs to oil viscosity along with the argument that when it's -40* here and I have to head to work running late without having my truck plugged in and under a minute warm up time, I can assure anyone that the oil is thicker than any motor oil at operating temperature yet my vvt and other oil driven accessories function fine. Slower but still functional.

I don't know if there's more to the story like his dad only doing 2 km short trips with the truck in drive and engine at wot before the starter fully disengages or what but I trust his word. I have a hard time wrapping my head around the thick oil causing the issue but it's all I have to work with.

 

[Foxtrot08]

No you didn't know what you were saying ... and you don't really know what you're even saying when you claim it's "pressure vs volume".


I simply described how an engine oiling system works. It's really quite simple for anyone who understands basic fluid dynamics.


Deflection tactic. You're the guy who brought up "pressure vs volume".


A billion miles from ever happening in an engine. So what's the point? Just more deflection from the actual focus of the discussion.


Nothing in an engine oiling system is related to an "ideal gas theory". So you are still way off base, even at a 38K foot view. "Pressure vs volume" isn't a "verses" ... they behave in harmony together. If you want more volume you need more pressure, all other factors being constant. It's simple fluid dynamics. Same princoiple applies to water flowing in your plumbing, or water flowing through a garden hose.


Anyone should know that heating up oil is going to decrease the viscosity ... so what. I'm talking about steady-state conditions. Fact is, and always will be that in an oiling system if you want more flow volume you need more pressure, viscosity held constant of course. If the viscosity decreased because of heat that the volume is constant, then the pressure decreases ... but since the volume is constant the part are still getting adequate lubrication. The pressure can be anyplace on the spectrum as long as the flow volume is adequate to lubricate the engine

You literally have no actual idea what you’re talking about. It’s pretty awesome.

Kudos.

Yes. They do behave in harmony together… pressure vs volume. And no, it’s not like a water pipe. Unless you’re describing a closed circuit system, which an engine is not. As you, so aptly described earlier. What you just described would be a closed loop system.

Pressure can be any place on the spectrum as long as the flow of volume is adequate to lubricate an engine… okay. Sure. Have fun with that idea.

I’m not deflecting at all. I’m literally replying with physics and engineering evidence, citations and formulas. Your story now, since you picked a fight with me again, has changed every post. I’m going to go enjoy UFC 213. You do you. OP has already responded that my response made sense. Case closed. I get you don’t like me, it’s alright. About 50% of people I’ve ever met don’t for any number of reasons. If you don’t get the whole idea of pressure vs volume. I apologize. I’ll try to make it better next time.

 

[ZeeOSix]

My point is essentially that, if we were to run overly thick oil, on the notion that "thicker oil provides more cushion between parts, and more cushion is always best for an engine", well, can we really make that statement?

Yes, the statement has been proven through controlled experimentation - ie, engine wear studies. Engine protection and wear mitigation with respect to viscosity is dependent on the film thickness between moving parts. More HTHS viscosity results in more film thickness, which separates moving parts more, thereby reducing the friction and wear of those parts.

Foxtrot's example of the 3" gear driving very thick oil both when cold and then when preheated matches the spirit of my original post very well. That's exactly what I'm talking about

As long as an adequate oil volume is supplied to moving parts, then they will be properly lubricated ... as long as the right oil viscosity is used for the use conditions.

 

[ZeeOSix]

You literally have no actual idea what you’re talking about. It’s pretty awesome.

Kudos.

I think there should be a breathalyzer on some keyboards, lol. You obviously are grasping at straws now, and it's obvious you don't really understand how an engine oiling system works, and certainly not much about fluid dynamics, even though you claim to be some physic "expert".

Yes. They do behave in harmony together… pressure vs volume.

It's pressure and volume ... behaving togther based on fluid dynamics.

And no, it’s not like a water pipe. Unless you’re describing a closed circuit system, which an engine is not. As you, so aptly described earlier. What you just described would be a closed loop system.

A water pipe is a flow restriction. Have you ever opened a faucet in your house and saw water flowing out of it, or saw water flowing out the end of a garden hose (a flexible "pipe"). What happens with flow out of the faucet or hose when the water pressure is increases on the main water line - yeah, the flow volume increases. Those are not a "closed" system - ie, a water line connected to a faucet or a garden hose with water flowing out the end of it. An engine oiling system isn't a closed system either. All the force fed oil eventually gets exited to ATM pressure inside the engine and falls back to the oil sump.

Pressure can be any place on the spectrum as long as the flow of volume is adequate to lubricate an engine… okay. Sure. Have fun with that idea.

It's true, as long as an adequate oil volume is reaching all the parts needing lubrication. If the oil pressure becomes too low .... guess what, you lose oil volume than also loose adequate lubrication. It's pretty simple to understand.

I’m not deflecting at all. I’m literally replying with physics and engineering evidence, citations and formulas.

And failed at that.

Your story now, since you picked a fight with me again, has changed every post. I’m going to go enjoy UFC 213. You do you. OP has already responded that my response made sense. Case closed. I get you don’t like me, it’s alright. About 50% of people I’ve ever met don’t for any number of reasons. If you don’t get the whole idea of pressure vs volume. I apologize. I’ll try to make it better next time.

I've said the same basic thing in all these posts, because that's the physics and the way an oiling system and lubrication behaves. Sad that some have some pretty big misconceptions on how it really works. No surprise though, as some misconceptions are hard to dissolve. I get the whole "idea of pressure vs volume", but you obviously really don't. Only 50%?, lol.

 

[Foxtrot08]

I think there should be a breathalyzer on some keyboards, lol. You obviously are grasping at straws now, and it's obvious you don't really understand how an engine oiling system works, and certainly not much about fluid dynamics, even though you claim to be some physic "expert".


It's pressure and volume ... behaving togther based on fluid dynamics.


Think again. Have you ever opened a faucet in your house and saw water flowing out of it. That's not a "closed" system. Either is a garden with water flowing out the end of it. An engine oiling system isn't a closed system either. All the force fed oil eventually gets exited to ATM pressure inside the engine and fall back to the oil sump.


It's true, as long as an adequate oil vollume is reaching all the parts needing lubrication. If the oil pressure becomes too low .... guess what, you lose oil volume than also loose adequate lubrication. It's pretty simple to understand.


And failed at that.


I've said the same basic thing in all these posts, because that's the physics and the way an oiling system and lubrication behaves. Sad that some have some pretty big misconceptions on how it really works. No suprise though, as some misconceptions are hard to disolve. I get the whole "idea of pressure vs volume", but you obviously really don't. Only 50%?, lol.

“What is a pressure tank for 100” Alec.

You don’t even know how water systems work. Why water towers exist. Why pressure tanks exist.

I’ll just end there. Because the rest isn’t even worth replying to.

 

[ZeeOSix]

“What is a pressure tank for 100” Alec.

You don’t even know how water systems work. Why water towers exist. Why pressure tanks exist.

I’ll just end there. Because the rest isn’t even worth replying to.

LoL ... really reaching now. I know exactly how water systems work, and not all use water towers, lol. It doesn't matter how pressure is produced ... pressure is pressure.

You should stop replying, because every one just makes you look worse with your knowledge of "physics".

 

[Foxtrot08]

LoL ... really reaching now. I know exactly how water systems work, and not all use water towers, lol. It doesn't matter how pressure is produced ... pressure is pressure.

You should stop replying, because every one just makes you look worse with your knowledge of "physics".

No, you don’t. It’s clear in the example you gave.

And you clearly have no clue how physics works. Or else you wouldn’t be replying in the way you have been. Using your HTHS example is part of that. As, you don’t actually know how HTHS conditions take place.

There are key things people say, that tell one when they don’t actually know what they’re talking about. And you gave several. Your posts are very project farm like. It’s at least good for entertainment. Thank you.

 

[ZeeOSix]

No, you don’t. It’s clear in the example you gave.

What example .. give the details of why you think it's wrong. More deflection when you know you're wrong 98% of the time.

And you clearly have no clue how physics works. Or else you wouldn’t be replying in the way you have been. Using your HTHS example is part of that. As, you don’t actually know how HTHS conditions take place.

What are you even talking about? Do you even understand what HTHS is and how that relates to MOFT and wear protection? You claim to be some kind of "oil expert" ... so you should know what HTHS viscosity is all about and how it relates to lubrication.

There are key things people say, that tell one when they don’t actually know what they’re talking about. And you gave several. Your posts are very project farm like. It’s at least good for entertainment. Thank you.

You have zero credibility with your so called knowledge about fluid dynamics and engine lubrication ... that's what I've concluded. Thank you for clearing that up.

 

[cheesepuffs2]

Yes, the statement has been proven through controlled experimentation - ie, engine wear studies. Engine protection and wear mitigation with respect to viscosity is dependent on the film thickness between moving parts. More HTHS viscosity results in more film thickness, which separates moving parts more, thereby reducing the friction and wear of those parts.


As long as an adequate oil volume is supplied to moving parts, then they will be properly lubricated ... as long as the right oil viscosity is used for the use conditions.

This is my entire point. So why do many members of this forum continue to imply on a regular basis that "thicker is just better" across the board to no end, when the bolded portion is the real truth?

"More HTHS viscosity results in more film thickness, which separates moving parts more, thereby reducing the friction and wear of those parts."

Lower viscosity oils reduce the internal friction of an engine, not the other way around. If you have adequate film thickness, then you have adequate film thickness. Going thicker than needed, after wear is reduced to the point of being negligible, which in tons of cases a 20 grade oil will accomplish, only adds internal friction and creates unneeded drag and higher temperatures.

We seem to ignore "as long as the right oil viscosity is used for the conditions" here an awful lot, to the point where newer car owners are stepping up multiple grades from new, when they only drive the car lightly around town anyway. This take lacks nuance here nearly everytime I see it regurgitated.

 

[ZeeOSix]

This is my entire point. So why do many members of this forum continue to imply on a regular basis that "thicker is just better" across the board to no end, when the bolded portion is the real truth?

The bottom line is a higher HTHS viscosity gives more film thickness between moving parts - many controlled test studies have shown that. Going up a grade, or going up two grades for track use is all about increasing the wear protection. Keeping the moving parts farther apart gives more MOFT headroom and more wear protection. It's that simple. If someone thinks they have enough MOFT then that's their decision without any real way to know. Going up a grade automatically gives more MOFT and results in more wear protection. For no real added cost, because the price of a jug of oil is not dependent on the viscosity printed on the jug.

"More HTHS viscosity results in more film thickness, which separates moving parts more, thereby reducing the friction and wear of those parts."

That's talking about friction from parts rubbing and wearing. That's different from the oil shearing friction. You get a trade off there. More shear friction from more film thickness, but less rubbing friction and wear at the same time. They may almost cancel each other out, why some don't see any fuel mileage change when going up a grade.

Lower viscosity oils reduce the internal friction of an engine, not the other way around. If you have adequate film thickness, then you have adequate film thickness.

Again, how do you know more film thickness wouldn't have been better ... until after the fact. Just like the guy who ran 5W-20 on the race track because he "thought the thinner oil would run cooler oil temps, and that would be a 'good' thing" found out first hand that 5W-20 was too thin to adequately protect the engine from excessive wear ... his journal bearings were really worn after a few sessions.

Going thicker than needed, after wear is reduced to the point of being negligible, which in tons of cases a 20 grade oil will accomplish, only adds internal friction and creates unneeded drag and higher temperatures.

That's up to the guy who owns the car to decide. Many that understand that running a grade thicker is basically a free upgrade to obtain added wear protection will go up a grade - many here do. Who wouldn't want that? I see zero loss in fuel mileage on the cars I've went up a grade on.

We seem to ignore "as long as the right oil viscosity is used for the conditions" here an awful lot, to the point where newer car owners are stepping up multiple grades from new, when they only drive the car lightly around town anyway. This take lacks nuance here nearly everytime I see it regurgitated.

It's their decision. Lots of people like headroom on stuff like that. As already mentioned, Ford bumped the specified viscosity up a grade on the Coyote ... so they threw CAFE credits down the tube for that move. If the 5W-20 was doing such a good job, why would they make a move like that. I recall reading on the Mustang forums of people who worked at Ford and said when the Coyote engine was being developed, the engineers wanted it to be specified with 5W-30 for added engine protection, but 5W-20 won out in the USA due to CAFE most likely (Australia got 5W-30) . Now a decade later they must have seen enough real world results to finally put in what viscosity it should have had from day one - 5W-30. If tracking that car, I'd go with 0W-40. Even for hard street use, the 5W-30 is good.

 

[cheesepuffs2]

The bottom line is higher HTHS viscosity gives more film thickness between moving parts. Going up a grade, or going up two grades for track use is all about increasing the wear protection. Keeping the moving parts farther apart gives more MOFT headroom and more wear protection. It's that simple. If someone thinks they have enough MOFT then that's their decision without any real way to know. Going up a grade automatically gives more MOFT and results in more wear protection.

Yes, I'm aware of what MOFT is, thanks.

Again, how do you know more film thickness wouldn't have been better ... until after the fact. Just like the guy who ran 5W-20 on the race track because he "thought the thinner oil would run cooler oil temps, and that would be a 'good' thing" found out first hand that 5W-20 was too thin to adequately protect the engine from excessive wear ... his journal bearings were really worn after a few sessions.

How do you know that it isn't enough in most cases? This forum is mostly comprised of daily commuters. The vast majority of vehicles on the road are getting oil changes at shops that are simply using the grade of oil that is printed on the fill cap, and I'm not seeing a glut of cars on the side of the road with lubrication-related engine failure.

Track usage has it's own challenge of keeping oil temperature within the proper window for the viscosity that has been chosen. Clearly in your example, they didn't have enough oil cooling for a 5W-20 under their conditions. That means next to nothing on BITOG for Joe Average here that's indicating concern of whether a 20 grade oil is enough to protect their low power-density grocery getter or not.

That's up to the guy who owns the car to decide. Many that understand that running a grade thicker is basically a free upgrade to obtain added wear protection. Who wouldn't want that? I see zero loss in fuel mileage on the cars I've went up a grade on.

Nn argument here, but my point this entire time since the OP is that this often isn't stated here as "a grade thicker" but rather, "thicker is better to no end", which is misleading.

It's their decision. Lots of people like headroom on stuff like that. As already mentioned, Ford bumped the specified viscosity up a grade on the Coyote ... so they threw CAFE credits down the tube for that move. If the 5W-20 was doing such a good job, why would they make a move like that. I recall reading on the Mustang forums of people who worked at Ford and said when the Coyote engine was being developed, the engineers wanted it to be specified with 5W-30 for added engine protection, but 3W-20 won out in the USA (Australia got 5W-30) due to CAFE most likely. Now a decade later they much have seen enough real world results to finally put in what viscosity it should have had from day one.

One data point (one engine in one model of car from one manufacturer) means nothing to me and adds nothing of value to this conversation. Ford chose wrong and then rectified a situation. Okay? Now that they call for 5W-30 for regular duty, non-track usage, should the owners daily driving these cars step up to a 40 grade just for extra headroom too?

 

[chris719]

One data point (one engine in one model of car from one manufacturer) means nothing to me and adds nothing of value to this conversation. Ford chose wrong and then rectified a situation. Okay? Now that they call for 5W-30 for regular duty, non-track usage, should the owners daily driving these cars step up to a 40 grade just for extra headroom too?

Well, I like to look at it through the lens of what would be technically ideal if cost and fuel economy are not considerations. I would run a 0W-40 ESP X3/X4 in that engine and I think there are zero downsides other than the cost of the oil. I believe many GM/Ford engines calling for 5W-30 would spec 0W-40 if they wanted the dealers and owners to have to pay for it.

 

[Foxtrot08]

What example .. give the details of why you think it's wrong. More deflection when you know you're wrong 98% of the time.


What are you even talking about? Do you even understand what HTHS is and how that relates to MOFT and wear protection? You claim to be some kind of "oil expert" ... so you should know what HTHS viscosity is all about and how it relates to lubrication.


You have zero credibility with your so called knowledge about fluid dynamics and engine lubrication ... that's what I've concluded. Thank you for clearing that up.

You should know since you’re quoting HTHS, that you made my point.

HTHS tests are done under fixed volume. Because, if you increased volume, you would decrease pressure. And you would remove the situation.

This is why the HTHS viscosity measured in mpa or cP. cP is literally Dynamic viscosity dimensions of force x time/volume.

So, if you increased volume, you would decrease pressure. Thus decreasing the force. And you would also be decreasing the amount of time, the force is applied to the area.

So… who doesn’t have a clue again? I mean, that’s literally what I’ve been saying…

 

[ZeeOSix]

How do you know that it isn't enough in most cases? This forum is mostly comprised of daily commuters. The vast majority of vehicles on the road are getting oil changes at shops that are simply using the grade of oil that is printed on the fill cap, and I'm not seeing a glut of cars on the side of the road with lubrication-related engine failure.

Most people taking their car to Iffy Lube don't even understand multi-viscosity oil or even what the "W" grade really means. How do you think they are going to understand the relationship between viscosity, film thickness and engine wear?

Nobody here has claimed that using the specified oil is going to result in an "engine failure". This is something the thinnie fans seem to latch onto whenever someone simply says that thicker oil gives more wear protection. It's funny.

Track usage has it's own challenge of keeping oil temperature within the proper window for the viscosity that has been chosen. Clearly in your example, they didn't have enough oil cooling for a 5W-20 under their conditions. That means next to nothing on BITOG for Joe Average here that's indicating concern of whether a 20 grade oil is enough to protect their low power-density grocery getter or not.

Ford speds 5W-50 for track focused Mustangs. All Coyotes have a coolant-to-oil cooler. They now spec 5W-30 for normal street use. So the grade increase is not for the reason you think. If it was a lack of oil cooling, they would have made the oil cooler better 10 years ago and keep that 5W-20 for CAFE credits.

Nn argument here, but my point this entire time since the OP is that this often isn't stated here as "a grade thicker" but rather, "thicker is better to no end", which is misleading.

Many that understand it will say a grade up will be beneficial. Who here has claimed that you need to run 20W-60 to get better engine protection?

One data point (one engine in one model of car from one manufacturer) means nothing to me and adds nothing of value to this conversation. Ford chose wrong and then rectified a situation. Okay?

Yeah, they chose wrong ... they chose too thin and instead thought they could push the envelope to get CAFE credits. It probably cost them some warranty work and more money over the years than they saved in CAFE credits. Why else would they bump up the specified viscosity in the USA?

Now that they call for 5W-30 for regular duty, non-track usage, should the owners daily driving these cars step up to a 40 grade just for extra headroom too?

Yes they should for track use ... maybe even go with 5W-50 as Ford specs for their track-pack cars. As I already said, 5W-30 is good for even hard street use.

 

[ZeeOSix]

You should know since you’re quoting HTHS, that you made my point.

I know exactly what it is.

HTHS tests are done under fixed volume. Because, if you increased volume, you would decrease pressure. And you would remove the situation.

Wow ... "done under fixed volume"? You are messed up with what you think you know. Go do some research on what HTHS viscosity really is, how it's tested and how it relates to lubrication inside an engine.

This is why the HTHS viscosity measured in mpa or cP. cP is literally Dynamic viscosity dimensions of force x time/volume.

Wow, you finally got something half right. "mpa" is not units of dynamic viscosity ... it's Pascal-seconds (Pa·s) or MPa-second (MegaPascel-second). cP is correct ... so only half credit, lol.

So, if you increased volume, you would decrease pressure. Thus decreasing the force. And you would also be decreasing the amount of time, the force is applied to the area.

That has absolutely nothing related to HTHS viscosity, or even an engine oiling system. You're still stuck on Boyle's Law, somehow thinking it applies to this discussion. It clearly doesn't.

So… who doesn’t have a clue again? I mean, that’s literally what I’ve been saying…

You still don't have a clue what you're talking about.