OVERKILL
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OK, I'll bite, how are we increasing flow, assuming a traditional positive displacement oil pump that isn't on the relief?
Kirkland 5W-20 vs 0W-20
- Thread starter glenncarpenter
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In theory, the thinner the oil is, the less turbulence you’re going to create in the oil channels and valleys. This will allow you to get oil, to where it’s needed, faster. Where as a thicker oil, in theory, will via friction, “bind” the system up more. Attached is the math to do a simple Reynolds’s number. However, an engine is a complex system - not just a linear system. So the math isn’t straight forward. You would have to do it for each part of the engine. (Which, I assume the engineers take this into account. I could be wrong.)
Given an engine is a dynamic sump, you’re not going to have instant film thickness everywhere - as we don’t have a pre-pump to develop a film on the bearings. As well, part of the engine is lubricated by gravity of the oil.
https://www.stle.org/files/TLTArchi...bsiteKey=a70334df-8659-42fd-a3bd-be406b5b83e5
As we can see from this article, the majority of wear still comes from lack of lubrication. For the first few critical seconds, you have lack of lubrication. The faster - even if it’s fractions of a second - you can get proper boundary lubrication to critical parts, the better off your engine is.
Also, while not straight forward. Filtration effects flow rates.
https://www.machinerylubrication.com/Read/53/oil-filter-performance
It does not effect filter performance unless you’re in a condition of extremes. But filters, will slow flow as well.
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Beg to differ. Beginning with the proposition that any commercially available oil will be beyond fine, and that Kirkland as a brand has a reputation for excellent quality at low prices, the question of how the Kirkland oils compare, and how they compare to other oils, is reasonable. As others have pointed out, it's extremely unlikely to make any difference at all. But interesting, at least to me.
For API SP it's D6335 (Teost 33c), and it allows up to 30 mg. 0W-20 oils are exempt from this test.
Just because it’s exempt doesn’t mean it’s not still done in development.
A lot of tests that aren’t mandatory are done.
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No doubt - and I'm sure many of those angles make exactly my point. Obviously depends on dozens of variables, so not a simple question and no simple answers. For me, few short trips, mostly moderate around-town trips, quite a few very long (road) trips, I have every reason to believe the vast majority of engine wear is under fully-warmed conditions. But would like to see actual data on this; best I can find is UOAs on this site, and I see little evidence there of the startup myth being true.
OVERKILL
$100 Site Donor 2021
OK, this is all related though. With a positive displacement pump, which the majority of engines are equipped with, they displace a given amount of oil every rotation, regardless of viscosity, assuming the relief isn't engaged. Same with the filter, while the filter is a "resistor" in series with the rest of the system, its impact on flow is only relevant if the pump is on the relief, at which point some of the volume the pump is moving is being bypassed back to the feed side of the pump and additional resistance from the filter could increase the amount bypassed.
Of course engines aren't "dry" when they are shutdown. There is still a film that coats everything. Probably the most vulnerable parts I can think of are the pistons/cylinder walls, which, since they are lubricated by oil sprayed from the sides of the rod bearings, suffer from poorer lubrication when the oil is heavier and doesn't spray as well. Anywhere that is delivered oil under pressure receives lubrication quite rapidly as the pump pressurizes the system, including lifter bores, rockers...etc.
Interesting discussion though, and one @kschachn myself and @ZeeOSix have engaged in a few times, so if you'll humour us, I expect this will develop a bit further as they chime in
Pretty much any oil flow in an engine's oiling system is turbulent flow when the flow rate is in GPM. When you do a Reynold's number calculation, it really doesn't take much to make any flow go turbulent. So all of that is out the window.In theory, the thinner the oil is, the less turbulence you’re going to create in the oil channels and valleys. This will allow you to get oil, to where it’s needed, faster. Where as a thicker oil, in theory, will via friction, “bind” the system up more. Attached is the math to do a simple Reynolds’s number. However, an engine is a complex system - not just a linear system. So the math isn’t straight forward. You would have to do it for each part of the engine. (Which, I assume the engineers take this into account. I could be wrong.)
Given an engine is a dynamic sump, you’re not going to have instant film thickness everywhere - as we don’t have a pre-pump to develop a film on the bearings. As well, part of the engine is lubricated by gravity of the oil.
https://www.stle.org/files/TLTArchi...bsiteKey=a70334df-8659-42fd-a3bd-be406b5b83e5
As we can see from this article, the majority of wear still comes from lack of lubrication. For the first few critical seconds, you have lack of lubrication. The faster - even if it’s fractions of a second - you can get proper boundary lubrication to critical parts, the better off your engine is.
Also, while not straight forward. Filtration effects flow rates.
https://www.machinerylubrication.com/Read/53/oil-filter-performance
It does not effect filter performance unless you’re in a condition of extremes. But filters, will slow flow as well.
All of this discussion needs to be under the premise that the oiling system is fed by a PD oil pump. At the same flow rate, the oil pressure goes up because the oil is more viscous. In fact, the oil pressure is actually directly proportional to the HTHS viscosity of the oil, not the KV100 viscosity. I posted this graph in a different thread the other day.
It's been said many times ... the oil filter will not effect the oil flow or the oil pressure downstream of the oil filter (where most oil pressure sensors are located) unless the PD oil pump is in pressure relief, which hardly happens except under certain rare conditions. If anything, that's not "straight forward" for most because it takes some knowledge of how PD pumps and oiling systems work. An engine oiling system is not like the water distribution system in you house. A clogged filter on the main line coming into your house will decrease the pressure and flow, but the water system in your house is not fed by a PD water pump that is not in pressure relief.
I ran 5 or 6 different brand oil filters on my Z06 (with the same Mobil 1 5W-30 oil) and every one of those filters showed the same exact oil pressure at the same oil temperature and engine RPM test points. The pump never hit pressure relief, so the oil pressure at the sensor read the same because the oil flow rate and oil temperature was the same.
And oil filters do not "slow the oil" flow ... not when there is a PD oil pump forcing the same oil volume through the filter and oiling system. Maybe in your house like mentioned above, but not in an engine if the pump is not in relief. FYI ... a typical oiling system is 15 times more flow restrictive than the typical oil filter, so most oil filters are vertically invisible to the oiling system. Oil filters typically only produce about 1-2 PSI of delta-p at low engine RPM, and around 5-8 PSI of delta-p at near redline which might be a flow rate of around 8 to 10 GPM. This is with hot oil (200F) of course.
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Of course engines aren't "dry" when they are shutdown. There is still a film that coats everything. Probably the most vulnerable parts I can think of are the pistons/cylinder walls, which, since they are lubricated by oil sprayed from the sides of the rod bearings, suffer from poorer lubrication when the oil is heavier and doesn't spray as well. Anywhere that is delivered oil under pressure receives lubrication quite rapidly as the pump pressurizes the system, including lifter bores, rockers...etc.
Interesting discussion though, and one @kschachn myself and @ZeeOSix have engaged in a few times, so if you'll humour us, I expect this will develop a bit further as they chime in
I mean, you just made my post for me:
Majority of engine wear happens during start up, and warm up till operational temperatures.
Assuming a PD pump, we can all agree on that. But as oil channels change sizes, you are going to have restriction of oil volume.
However, everything you just said is going to produce wear. Your anti wear additives aren’t activated till 160f~ish. You’re not going to have the proper oil volumes on critical parts (as mentioned) and the initial oil film will be wiped off rather quickly. Within the first few revolutions. How long can that oil’s elastohydrodynamic film thickness last before new oil gets in there and we go back to boundary lubrication? Or is wear going to be produced?
Given, OEM engineers should have this calculated in when designing metal surfaces. And there is also the argument of pre-lubricated parts with different coatings in modern technology. However: a PD pump isn’t going to get oil, everywhere, instantly, at the proper quantities.
At 12gpm, at operation temperature of the oil, You’re moving 1 quart a second, give or take. Now we’re talking about “cold” flow - what volume of oil is the pump actually moving? When is there enough oil to flood the entire system? Add in everything else I mentioned previously.
Now, if you use a lower viscosity, multi weight product - why would you not? It literally moves faster in drip down applications (such as piston skirts.) or splash lubricated parts.
Thus, more wear when at cold flow - specifically on start up. This is why large industrial systems have pumps that pre-charge the systems with at least some pressure.
We can also get into the idea that fluid friction also causes wear in certain areas - such as pumps - but that’s really splitting hairs.
So to my original statement - 0w20 does everything 5w20, but it does it better.
Edit:
I messed up the quotes somehow.
There has never been a question with engines having a PD pump or not.
Simply my statement: 0w20 does everything a 5w20 does, but better. And you have more wear on start up.
Oil filters should not ever “slow down” oil because of where it’s located at in the oil loop of the system.
That can be said with even with 0W-xx because cold 0W oil is still a 100+ times thicker than xx at 200F.
You know about the SAE J300 "CCS" and "Pumpability" viscosity specs? You know why they exist? Why aren't vehicles in the northern states and Canada, etc in the junk yards way earlier than in other warmer parts of the Earth?
When and engineer designs an oiling system, the channels are sized for the required oil flow volume. The PD pump will maintain the same basic oil volume distribution as long as the pump is not in relief.
Of a PD oil pump puts out 5 GPM at 3000 RPM, then it puts out 5 GPM unless the pump is in relief ... regardless of the oil viscosity. But of course, if someone revved the engine to 6000 RPM 5 seconds after a cold start in the winter, the pump would probably hit relief, but there would probably still be enough oil volume flowing to provide adequate lubrication. Those engineers have thought about that, and that's on factor involved when setting an oil pump pressure relief setting.
Yes, in areas of the system that depend on splash or non-pressurized delivery from the pump, a too thick of oil could cause lubrication issues. But again, think about why the "W" rating exists and why engineers specify a certain W rating oil for their design. So son't run 20W-xx in Minnesota in the middle of winter and expect cold start-ups to be adequately lubricated.
Except maybe in the mechanical shearing department due to VIIs. There's only a 5C "CCS and Pumpability" spec difference in SAE J300 between 0W and 5W.
You come across as not fully understanding an engine oiling system, and my comments were focused on that.
You specifically said earlier that "Filtration effects flow rates". In an engine, a filter will not, and I explained what conditions that can only happen which is very rare. In your house water system ... yes a filter can effect flow rates and pressure.
OK, this is all related though. With a positive displacement pump, which the majority of engines are equipped with, they displace a given amount of oil every rotation, regardless of viscosity, assuming the relief isn't engaged. Same with the filter, while the filter is a "resistor" in series with the rest of the system, its impact on flow is only relevant if the pump is on the relief, at which point some of the volume the pump is moving is being bypassed back to the feed side of the pump and additional resistance from the filter could increase the amount bypassed.
Of course engines aren't "dry" when they are shutdown. There is still a film that coats everything. Probably the most vulnerable parts I can think of are the pistons/cylinder walls, which, since they are lubricated by oil sprayed from the sides of the rod bearings, suffer from poorer lubrication when the oil is heavier and doesn't spray as well. Anywhere that is delivered oil under pressure receives lubrication quite rapidly as the pump pressurizes the system, including lifter bores, rockers...etc.
Interesting discussion though, and one @kschachn myself and @ZeeOSix have engaged in a few times, so if you'll humour us, I expect this will develop a bit further as they chime in
Because we have better oils now. Metallurgy, etc. Sorry, I don’t appreciate the talking down to. You still see premature wear in cold weather start ups of large equipment up there. Which is why they don’t shut down certain things. And there’s been heavy advancements of low pour synthetics for cold weather industrial applications.
None of what you’re saying here changes my point: less wear happens, when you use a 0wXX product.
None of this is relevant to my statement. And I’ve mentioned that in passing thus, my statement about engineers talking this into account.
So… you’re agreeing with me?
Arguing about VII’s without knowing proprietary information on blending and formulation isn’t something I would rest my hat on.
My statement still stands. 0w20 does everything 5w20 does, but better. And you still get more wear on start up.
I’m very aware of how they work.
I’m also very aware of how hydrodynamic lubrication works. And how EHL plays into start up wear.
Like I previously said, all cold start-ups can produce some level of wear. You have any formal test study links that show that if 0W is used instead of 5W when both are acceptable W ratings that the 0W will show measurable wear differences? I'm just stating fact about oiling systems, if someone doesn't seem to fully grasp their operation i will say so.
Obviously, if lubrication depends on non-pressurized deliver that a much thicker oil will not move as fast and well. There really isn't much difference between a 0W and 5W per SAE J300 specs. The difference would be seen way down at like -30C. But certainly not at temperature way above that.
Compare the KV100 to HTHS ratio, it would show some VII affect in the temporary shear department, which does matter in high shear areas of the engine. At high shear rates, it could be that a 0W-20 produces more wear than a 5W-20 under the same conditions ... and that would be during 99.99% of the engine operation time, not the fraction of a percent at cold start-up.
I wouldn't automatically conclude that, because the hot operation of an engine time is much longer that cold start-up operation time. There's more to the big picture than just cold start-ups. We could also dive into the cleanliness level of the sump based on the efficiency of the oil filter used.
I'm still waiting for someone to link that study that say cleaner oil doesn't result in less engine wear.
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Honestly, from your postings it really doesn't come across that way. Sorry, but that's how it looks. You wouldn't have said some of the things you did if you fully understood a PD pump fed oiling system. Even Overkill picked up on that based on his responses.
You assumed something. I did not.
You’re looking like someone that doesn’t understand different types of lubrication. But I’m assuming you do, which perhaps might be my fault for making a positive assumption.
You wouldn’t be asking me for test data of a 0w vs a 5w, if you positively knew boundary conditions inside of an engine. Should we break down the different steps?
We could also bring in particulate wear in initial start up conditions. However, will that lower a B10 for a normal car? No. It’s a pretty easy blanket statement to say 0w20 > 5w20.
I didn't assume anything ... I read what you posted. What you posted previously does not show you fully understand an engine oiling system fed by a PD pump. Nothing you can say will change the words you already posted.
I asked for the data, because without it you're just assuming that's true in all situations. What about the wear test data of a 0W-20 vs a 5W-20 at high shear conditions and very hot areas in the engine? ... like the ring pack. Assuming the KV100 is exactly the same between the two.
Let's hear about these "boundary conditions" inside of an engine. Most here know the 3 different realms of lubrication.
Saying 0W-20 is better than 5W-20 can not be concluded without some proof. Like I said, at -30C it might be, but any time you are above the min W rating temperature of 5W I highly doubt you will see the difference ... unless you have the test data to prove it.
See my previous post.Like I previously said, all cold start-ups can produce some level of wear. You have any formal test study links that show that if 0W is used instead of 5W when both are acceptable W ratings that the 0W will show measurable wear differences? I'm just stating fact about oiling systems, if someone doesn't seem to fully grasp their operation i will say so.
But there is a difference. And you might as well take advantage of it, especially when it is priced the same.
Which, again all depends on the formulation. Which, goes to the additives used and how they are formulated.
Assuming OP’s post is correct, I’m fairly familiar with the blends used by Warren and the additives used. You’re not going to find what you’re referring to in normal usage of a normal PCEO application. You’re going to find more wear on start up.
I wouldn't automatically conclude that, because the hot operation of an engine time is much longer that cold start-up operation time. There's more to the big picture than just cold start-ups. We could also dive into the cleanliness level of the sump based on the efficiency of the oil filter used.
Depends on usage of the vehicle.
But there won’t be a study that ever says cleaner oil causes more wear. I linked a study earlier that says directly opposite of that earlier. #1 wear is lack of lubrication (start up) #2 is contamination.
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