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

[cheesepuffs2]

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?

When did I imply that most people understand the relationship between viscosity, film thickness and engine wear? My point was the opposite, that the vast majority of car owners have their heads in the sand, yet do not experience excessive engine wear, displaying that bumping up in reaction to this boogeyman issue is pointless.

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.

Most "thickies" here are overly concerned owners of mundane engines that are spending time and energy trying to figure out a solution to a problem that doesn't exist. Stressing that if they don't go thicker than what the manual says that they'll experience excess engine wear. The reality is that cars end up in the junkyard due to just about every reason aside from a hair more bearing wear, if that's even occurring at all, due to thinner oil.

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.

You are completely inferring something from my response other than what I wrote.

I never equated your track use 20 grade example to oil grade specified for the Coyote. You gave two different examples, not even specifing what kind of car had the issue using 20 grade on track. I already said, I don't really care about the Mustang example, because that isn't a direct comparison the generalizations that are made on this forum. That's one situation for an OEM to sort out, and they did. Cool. Next.

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?

Again, you are entirely missing the point. My whole basis of this is that people recommend going thick with no ceiling on at what point it may become a detriment.

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?

Have we beaten this horse enough yet?

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.

I've referenced multiple times now how this forum is mostly comprised of basic transportation applications. You're grasping for a rebuttal to an argument I never made.

 

[ZeeOSix]

When did I imply that most people understand the relationship between viscosity, film thickness and engine wear? My point was the opposite, that the vast majority of car owners have their heads in the sand, yet do not experience excessive engine wear, displaying that bumping up in reaction to this boogeyman issue is pointless.

I didn't claim you implied that most people understand the relationship between viscosity, film thickness and engine wear? I simply said the mass majority if people, especially those who go get their oil changed by some place, and even people here and on social media like YT simply don't understand that relationship. After years of discussion the light bulb seems to go on for some though.

Most "thickies" here are overly concerned owners of mundane engines that are spending time and energy trying to figure out a solution to a problem that doesn't exist. Stressing that if they don't go thicker than what the manual says that they'll experience excess engine wear. The reality is that cars end up in the junkyard due to just about every reason aside from a hair more bearing wear, if that's even occurring at all, due to thinner oil.

Maybe only the ones who understand that going up a grade provides more wear protection headroom. Based on the information given, they can then make up their own mind if that's something they want to do. If they do, there's no harm in doing so, only the benefit of added engine protection is the result. What's wrong with that? Somehow people think doing something like that is "wrong". If they understood the physics they probably wouldn't see it that way.

You are completely inferring something from my response other than what I wrote.

I never equated your track use 20 grade example to oil grade specified for the Coyote. You gave two different examples, not even specifing what kind of car had the issue using 20 grade on track. I already said, I don't really care about the Mustang example, because that isn't a direct comparison the generalizations that are made on this forum. That's one situation for an OEM to sort out, and they did. Cool. Next.

I gave examples to help equate the benefit of higher HTHS viscosity - nothing more. The generalization is that any engine using 5W-20 or less can achieve more engine protection from going up a grade, and many here do just that. That's a fact, regardless if you think the added protection from more film thickness is needed or not. If someone doesn't want to wonder if the thinner oil is good enough for their use conditions, then the simple thing to do is go up a grade. There is absolutely nothing wrong by doing that. And anyone thinking going up a grade is going to harm their engine doesn't know much about engine lubrication.

Again, you are entirely missing the point. My whole basis of this is that people recommend going thick with no ceiling on at what point it may become a detriment.

What "determent"? Who has recommended going thick with "no ceiling". I haven't seen it like that. Nobody here is saying to use 20W-60 in anything for instance, except for those BMWs that specify it, lol.

Have we beaten this horse enough yet?

You tell me ... yes, it's pretty much going in circles now, lol. I'm sure this thread will be locked soon due to "technical bickering".

I've referenced multiple times now how this forum is mostly comprised of basic transportation applications. You're grasping for a rebuttal to an argument I never made.

The only argument and claim I've made is that thicker oil results in more wear protection. Simple as that, nothing more. Take it or leave it is everyone's own decision. But the facts of physics and Tribology wrt viscosity, film thickness and wear protection due to the viscosity factor can't be changed. If someone wants to run what's on the oil cap, then go for it. If they want to put 0W5 or WD-40 in something specifying 5W-30 then go for it ... it's not my vehicle.

 

[Foxtrot08]

I know exactly what it is.


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.


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.


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.


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

https://cdn.standards.iteh.ai/samples/106384/cdbed48c199248fbbfd2542b6df84c57/ASTM-D4683-20.pdf


Literally right there.


It’s been fun.

 

[OVERKILL]

There were actually old ICEs that simply fed the journal bearings oil simply under the force of gravity - no oil 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.

Sorry I missed all the excitement on here last night, watched some movies and had a lovely time with my wife. This conversation between you two became absolutely toxic, I don't think linking the gravity oiled engine discussion is going to do anything to salvage it.

"Pressure vs flow" and "Pressure and flow" and yet nobody mentioned the pump being on or off the relief

Anyway, I'm not wading into this dumpster fire, my mental health is good this weekend and I'd like to keep it that way.

 

[Brian123]

I'll help Op out here because I feel like his question is misunderstood... How thick is too thick of a viscosity before it's doing more harm than good.

This is a story I heard from my co-worker and fellow mechanic who is also a thickie... allegedly his elderly father took some new synthetic 20w-50 motor oil that was kicking around and did an oil change on his truck with it in the summer. Apparently a tank or two of gas later the engine had oil pressure issues, took it in to the dealership and the main and conrod bearings were discoloured and heavily worn. Not shredded, just worn and discoloured. It was either a 5.4 or 5.0 Ford in an F150.. I don't remember. He told them what happened and they helped him out by getting it covered under warranty but the reason the mechanic on the job provided the customer off the record was that apparently those engines have too tight a tolerance for such a thick oil and that 40 wt is the max they can reliably run.

I wasn't there and i'm skeptical of that reasoning but I fully trust my coworker and have no hands on experience with the engine in question so I'm not gonna comment further. Just throwing this out there of me hearing about a case of lubricant being too thick to application.

Joba27n: Thank You for this story!
There is quite a bit of unknowns in this story:
1) How many miles on the Engine
2) What were the previous OCI's like
3) What spec oil was used before the 20W-50 synthetic was put in.

Another thought here is, and it is a thought since I am not going to look the specs up, Ford did have the Coyote Motor use 5W-50 on some Track Package that they had. Ford did not spec a 20W-50 and I am willing to bet that the 5W-50 is not as thick.

There are members here that are using 0W-40 and 5W-40, 20W-50 is way too thick. JMO

 

[OVERKILL]

Joba27n: Thank You for this story!
There is quite a bit of unknowns in this story:
1) How many miles on the Engine
2) What were the previous OCI's like
3) What spec oil was used before the 20W-50 synthetic was put in.

Another thought here is, and it is a thought since I am not going to look the specs up, Ford did have the Coyote Motor use 5W-50 on some Track Package that they had. Ford did not spec a 20W-50 and I am willing to bet that the 5W-50 is not as thick.

There are members here that are using 0W-40 and 5W-40, 20W-50 is way too thick. JMO

Interestingly, Motorcraft 5W-50 has a KV100 of 21cSt, while Castrol GTX 20W-50 (just as an example, we don't know which one he used) has a KV100 of 17.8cSt. GTX High Mileage has a KV100 of 20.3cSt.

Now, the KV40 is much higher on these conventional 20W-50 lubes of course.

 

[Pablo]

I Didn’t read the entire thread.

 

[PontiacHO]

The thicker the better then…with wear associated with whatever spins the oil pump….

 

[Brian123]

Interestingly, Motorcraft 5W-50 has a KV100 of 21cSt, while Castrol GTX 20W-50 (just as an example, we don't know which one he used) has a KV100 of 17.8cSt. GTX High Mileage has a KV100 of 20.3cSt.

Now, the KV40 is much higher on these conventional 20W-50 lubes of course.

I am looking at Pablo's favorite oil, I am comparing 5W-50 to 20W-50 at 40 Degrees C the 5W-50 is 119.5 whereas the 20W-50 is 160.3
I am going to guess that the 5W-50 will be better at startup than the 20W-50, assuming the temp outside is 100 degrees, lower than 100 Degrees, I know the 5W-50 is better. LOL

Now at 100 Degree C the 5W-50 is 19.4 and the 20W-50 is 19.5

 

[4WD]

Sorry I missed all the excitement on here last night, watched some movies and had a lovely time with my wife. This conversation between you two became absolutely toxic, I don't think linking the gravity oiled engine discussion is going to do anything to salvage it.

"Pressure vs flow" and "Pressure and flow" and yet nobody mentioned the pump being on or off the relief

Anyway, I'm not wading into this dumpster fire, my mental health is good this weekend and I'd like to keep it that way.

Yeah - all over the place - mention of a water tower?
That’s height X 0.052 X 8.33 for pressure at the base. Call that the pump pressure - from there pipe ID is the big parasite - length is decay in psi/foot, and then each bend, etc…
But, with lube oil - ID (TFA) equivalent in the galleries is a fixed choke - bearings are entirely different physics - and linear response is not simple decay like pipe … Engines deal with flow distribution in a unique manner …
The few minutes to warm up does not warrant all this debate since a viscosity change in 2 digits is way down in single digit contributions to total system pressure …

 

[OVERKILL]

I am looking at Pablo's favorite oil, I am comparing 5W-50 to 20W-50 at 40 Degrees C the 5W-50 is 119.5 whereas the 20W-50 is 160.3
I am going to guess that the 5W-50 will be better at startup than the 20W-50, assuming the temp outside is 100 degrees, lower than 100 Degrees, I know the 5W-50 is better. LOL

Now at 100 Degree C the 5W-50 is 19.4 and the 20W-50 is 19.5

Yeah, totally depends on which oils you are contrasting for sure. I doubt any of the 20W-50's have a VI as high as the 5W-50, so they are all going to be heavier than the 5W-50's at 40C. I found it interesting that the KV100 for the Motorcraft 5W-50 is as high as it is (21cSt).

 

[ZeeOSix]

https://cdn.standards.iteh.ai/samples/106384/cdbed48c199248fbbfd2542b6df84c57/ASTM-D4683-20.pdf

Literally right there.

It’s been fun.

Where's the "done under fixed volume" claim. Testing an oil in the lab for HTHS has nothing to do with an oiling system is operating wrt pressure and volume. What you said last night made no sense ... and only got half credit for a partially right answer to dynamic viscosity units, lol.

 

[ZeeOSix]

"Pressure vs flow" and "Pressure and flow" and yet nobody mentioned the pump being on or off the relief

Even if the PD pump is in relief, if it can keep building pressure, which means it also will send more volume to the system. More pressure means more flow in a fixed flow resistance. No spring loaded PD oil pump pressure relief valve is a perfect control of pump output volume.

 

[cheesepuffs2]

Even if the PD pump is in relief, if it can keep building pressure, which means it also will send more volume to the system. More pressure means more flow in a fixed flow resistance. No spring loaded PD oil pump pressure relief valve is a perfect control of pump output volume.

How does it keep building pressure while in relief?

 

[ZeeOSix]

I am looking at Pablo's favorite oil, I am comparing 5W-50 to 20W-50 at 40 Degrees C the 5W-50 is 119.5 whereas the 20W-50 is 160.3
I am going to guess that the 5W-50 will be better at startup than the 20W-50, assuming the temp outside is 100 degrees, lower than 100 Degrees, I know the 5W-50 is better. LOL

Now at 100 Degree C the 5W-50 is 19.4 and the 20W-50 is 19.5

Of course a 5W is going to be better than a 20W at start-up. That's the whole purpose of the W rating to show which one will be thicker when cold. If people want to split hairs on which W rated oil is "thinner" they need to compare the actual CCS and MRV dynamic viscosity of the W ratings.

 

[OVERKILL]

Even if the PD pump is in relief, if it can keep building pressure, which means it also will send more volume to the system. More pressure means more flow in a fixed flow resistance. No spring loaded PD oil pump pressure relief valve is a perfect control of pump output volume.

*can* yes, but they are decoupled at that point. With the relief not in the picture, every rotation of the pump displaces a given volume of oil (ignoring slip and leakage for the sake of this discussion), with pressure simply being an artifact of the upstream system's resistance.

 

[OVERKILL]

How does it keep building pressure while in relief?

The relief is an orifice with a fixed maximum size. Only so much volume can be shunted through the relief before it starts producing enough back-pressure that observed combined pressure increases. This was readily observable on those old HV SBC pumps on a factory clearanced engine. Relief pressure was 55psi but on a cold start with 15W-40 in there you could see 80+psi because the relief was overwhelmed.

 

[ZeeOSix]

How does it keep building pressure while in relief?

A spring loaded relief valve can't open enough and shunt every drop of oil in order to keep the output pressure exactly constant.

Here's some LS oil pump curves from Melling showing where the pump starts going into relief, and it still keeps increasing in output pressure and volume after the relief valve starts to open. There has been some detailed discussions of this in other threads.

 

[ZeeOSix]

*can* yes, but they are decoupled at that point. With the relief not in the picture, every rotation of the pump displaces a given volume of oil (ignoring slip and leakage for the sake of this discussion), with pressure simply being an artifact of the upstream system's resistance.

It's never fully "decoupled". PD pumps with a spring loaded pressure relief do keep building some pressure and increasing output volume, as shown in the post above. You even pointed that out that aspect in post 97. It rolls over pretty good, but it's still building output volume and pressure.

 

[OVERKILL]

PD pumps with a spring loaded pressure relief do keep building pressure and increasing output volume, as shown in the post above. you even pointed that out in post 97.

Yes, but the relationship between the each rotation of the pump and the amount of oil entering the engine is decoupled was my point. It's a very simple relationship without the relief in the picture. Once you include the relief, then you have to factor in relief behaviour, like, as you noted, its varying capacity as it opens (cracks) until it hits full capacity (fully open), which makes the conversation a bit more complex.

On my Jeep for example, with 0W-40, it goes onto the relief (~65psi) on a below freezing cold start, but observed system pressure doesn't rise beyond relief pressure (so volume is being shunted, but that volume is able to be handled by the relief, so observed pressure doesn't increase) unless I increase engine RPM to the point where I overwhelm it. This is different from the SBC behaviour I described where the relief is overwhelmed immediately.

It's just another dimension to the discussion, my apologies if I wasn't sufficiently clear in how I was trying to frame it.