# Kirkland 5W-20 vs 0W-20

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 in the engine? 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.

Any time you’re hitting that rating you’ve already failed. I posted an article previously on that.

Secondly, decreasing viscosity can decrease friction which leads to less wear. Here is a study on it - warning, PDF.

Given, this is with piston rings. But you can take the same ideas to other areas.

Given, formulation differences, a Xw20 should be the same (approximate) viscosity at 212f. You will have less wear using a lower viscosity oil during the cold start phase.

^^^ The bottom line conclusion is if people use the appropriate W rating of oil as called out by the engine maker, the engine will outlast the car. The W rating exists for a good reason. That's a "blanket statement", and if people are paranoid about cold start-up wear, then use a 0W even if living in Florida.

^^^ The bottom line conclusion is if people use the appropriate W rating of oil as called out by the engine maker, the engine will outlast the car. The W rating exists for a good reason. That's a "blanket statement", and if people are paranoid about cold start-up wear, then use a 0W even if living in Florida.

I can’t find your study on the different aspects of lubrication boundaries online anymore. As the link I had is now dead. But - Alakhramsing, S. S., de Rooij, M. B., Schipper, D. J., & van Drogen, M. (2017). Elastohydrodynamic lubrica-on of coated finite line contacts. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

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That covers it.

Any time you’re hitting that rating you’ve already failed. I posted an article previously on that.

Secondly, decreasing viscosity can decrease friction which leads to less wear. Here is a study on it - warning, PDF.

Given, this is with piston rings. But you can take the same ideas to other areas.

Given, formulation differences, a Xw20 should be the same (approximate) viscosity at 212f. You will have less wear using a lower viscosity oil during the cold start phase.
There is a difference between "hydrodynamic friction" and "boundary contact friction". I'm talking about the latter, which your interesting paper basically concludes what I stated that if a 0W-20 has worse HTHS viscosity then there could be more wear in certain areas of the engine, which happens when there is more "boundary contact" ... when parts start rubbing on each other more and cause more contact friction and wear. That also causes the oil to become more contaminated, and therefore more 3-body wear can also happen. It can become kind of a run-away situation given the right circumstances.

"Results from these tests show that in general, the lower the viscosity of the oil, the lower the friction was in the hydrodynamic regime, due to the reduction in shear stress. However, this gain for lower viscosity came at the cost of allowing boundary friction to occur at higher speeds, at which point FMEP was increased."

"It is important to note, however, that decreasing viscosity also increases the amount of boundary contact friction on the liner, which can have negative effects such as increased wear which lead to higher maintenance costs in automotive application."

Look at Conclusion #1.

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There is a difference between "hydrodynamic friction" and "boundary contact friction". I'm talking about the latter, which your interesting paper basically concludes what I stated that if a 0W-20 has worse HTHS viscosity then there could be more wear in certain areas of the engine, which happens when there is more "boundary contact" ... when parts start rubbing on each other more and cause more contact friction and wear. That also causes the oil to become more contaminated, and therefore more 3-body wear can also happen. It can become kind of a run-away situation given the right circumstances.

"Results from these tests show that in general, the lower the viscosity of the oil, the lower the friction was in the hydrodynamic regime, due to the reduction in shear stress. However, this gain for lower viscosity came at the cost of allowing boundary friction to occur at higher speeds, at which point FMEP was increased."

"It is important to note, however, that decreasing viscosity also increases the amount of boundary contact friction on the liner, which can have negative effects such as increased wear which lead to higher maintenance costs in automotive application."

But assuming both products are in spec, you’re not decreasing viscosity. Again, you’re hitting at formulation properties. Which, for us are an unknown.

So we have to run with the idea that both products are fully formulated products. Thus, at operating temperatures, the same viscosity. Including, at HTHS. Which, is dependent on the additive formulation and base oils used.

A poorly formulated 5w20 could have a worse HTHS property than a well formulated 0w20.

Thus, my argument of assuming same HTHS.

Since Kendall posts their HTHS ratings - both the 0w20 and 5w20 are 2.6.

A poorly formulated 5w20 could have a worse HTHS property than a well formulated 0w20.

Thus, my argument of assuming same HTHS.

Since Kendall posts their HTHS ratings - both the 0w20 and 5w20 are 2.6.
And a badly formulated 0W-20 could have a worse HTHS than a better formulated 5W-20.

If they both have the same HTHS (and have the same AF/AW pack for anything below full hydrodynamic lubrication protection), then they should both protect equally. But that doesn't automatically mean "every 0W-20 is better than any 5W-20" like your blanket statement.

Then there is the whole "film thickness" vs "film strength" discussion. Film thickness is the main defense against moving parts from rubbing and wearing, and when the MOFT goes to zero then the "film strength" kicks in to mitigate wear. My thinking is never depend on film strength to save what film thickness (MOFT) should have done in the first place. This leads in to "thick vs thin" discussions, which we won't go into, lol.

All you could really conclude from the W rating is that 0W will allow the engine to crank better, and for the oil pump to pump the oil and distribute it well if the ambient temperature is close to the minimum CCS and Pumpabiltiy viscosity limits that SAE J300 shows for the specified temperature minimums. Will it actually reduce wear over a 5W that's used above the minimum temperature cut-off? Maybe if you're at very very cold temperatures ... but I'd have to see a very well controlled test to prove it. The W rating of oil is easy to decide on, and the HTHS is more important in the long run, as many studies show that more wear starts kicking in on some engine components when the HTHS goes below ~2.6 cP .... which is the typical HTHS of new un-sheared and un-diluted xW-20. But that's a whole other debate that has been discussed many times over.

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And a badly formulated 0W-20 could have a worse HTHS than a better formulated 5W-20.

If they both have the same HTHS (and have the same AF/AW pack for anything below full hydrodynamic lubrication protection), then they should both protect equally. But that doesn't automatically mean "every 0W-20 is better than any 5W-20" like your blanket statement.

Then there is the whole "film thickness" vs "film strength" discussion. Film thickness is the main defense against moving parts from rubbing and wearing, and when the MOFT goes to zero then the "film strength" kicks in to mitigate wear. My thinking is never depend on film strength to save what film thickness (MOFT) should have done in the first place. This leads in to "thick vs thin" discussions, which we won't go into, lol.

All you could really conclude from the W rating is that 0W will allow the engine to crank better, and for the oil pump to pump the oil and distribute it well if the ambient temperature is above what SAE J300 shows for the specified temperature minimum. Will it actually reduce wear over a 5W that's used above the minimum temperature cut-off? Maybe is you're at very very cold temperatures ... but I'd have to see a very well controlled test to prove it. The W rating of oil is easy to decide on, and the HTHS is more important in the long run, as many studies show that more wear starts kicking in on some engine components when the HTHS goes below ~2.6 cP .... which is the typical HTHS of new un-sheared and un-diluted xW-20.

I’m going to stick by my blanket statement currently. I’ve defended it (fairly) well I believe.

As you said, we’re getting into a lot of conversations that are significantly off point. And, if you want to have them - I’d probably prefer to have them over a beer (or a bourbon) and a cigar with you.

In my professional opinion, a well formulated 0w20, will be better than a 5w20. In this case, I believe this is the case when comparing two Warren products. As I know the base oils and their primary additive supplier for PCEO products.

That being said, I’m going to head to bed. It was a good debate, and I hopefully linked some good articles.

To the previously mentioned thick vs thin, and boundaries of lubricants - I did find the slides of the article. But not the full paper. Warning - pdf

It’s a fun read if you’re into that thing.

STLE has some amazing resources. While it’s not 0w20 vs 5w20 tests, that are easy to understand. It’s concepts that you can take, then apply elsewhere.

I’m going to stick by my blanket statement currently. I’ve defended it (fairly) well I believe.

As you said, we’re getting into a lot of conversations that are significantly off point. And, if you want to have them - I’d probably prefer to have them over a beer (or a bourbon) and a cigar with you.

In my professional opinion, a well formulated 0w20, will be better than a 5w20. In this case, I believe this is the case when comparing two Warren products. As I know the base oils and their primary additive supplier for PCEO products.
A "blanket" statement can always have lots of moth holes in it, lol. I don't smoke, but I'd have a drink or two with you.

To the previously mentioned thick vs thin, and boundaries of lubricants - I did find the slides of the article. But not the full paper. Warning - pdf

It’s a fun read if you’re into that thing.

STLE has some amazing resources. While it’s not 0w20 vs 5w20 tests, that are easy to understand. It’s concepts that you can take, then apply elsewhere.
That study is really only for roller bearing and line type of contact components with very high contact pressures involved in Elasto-Hydrodynamic lubrication, like components shown on page 6 ... and surface and surface coating hardness (to help minimize surface deformation) plays a big role. And it's only a model, not backed up by empirical testing, but interesting anyway. When talking about full hydrodynamic and mixed lubrication like in journal bearings and between most non-line contact moving parts, it's a different animal from that type of lubrication.

A "blanket" statement can always have lots of moth holes in it, lol. I don't smoke, but I'd have a drink or two with you.

That study is really only for roller bearing and line type of contact components with very high contact pressures involved in Elasto-Hydrodynamic lubrication, like components shown on page 6 ... and surface and surface coating hardness (to help minimize surface deformation) plays a big role. And it's only a model, not backed up by empirical testing, but interesting anyway. When talking about full hydrodynamic and mixed lubrication like in journal bearings and between most non-line contact moving parts, it's a different animal from that type of lubrication.

The presentation is just for fun, nothing directly applicable to the current discussion, besides maybe something like the crank shaft bearings.

I think I got rid of most of the moths of the argument though.

Trying to think this through... So base stock "thickness" comes into play for 0w vs 5w oils. Assume both (0w & 5w) base stock oils are derived from the exact same ingredients, how exactly would one base become thinner and the other thicker? At this point this is it true that there would be no VI's that come into play?

I still don't subscribe to the idea that a 0W-20 is always superior to a 5W-20. The only time I think that's applicable is when cranking in freezing temperatures.

Let's take a couple 20 grades with the same KV100.

I have a very hard time believing that flow is going to differ much anywhere above 0°C with these two oils. I think any difference would be trivial to even mention. The traction differences in the bearings between quality of base oils would likely have a greater impact on oil flow.

I liked Kirkland when it was \$24 or on sale for \$22 for 10 qts. Those days are gone.

Trying to think this through... So base stock "thickness" comes into play for 0w vs 5w oils. Assume both (0w & 5w) base stock oils are derived from the exact same ingredients, how exactly would one base become thinner and the other thicker? At this point this is it true that there would be no VI's that come into play?
One would be blended with a heavier version of the same base oil than the other is the simplest way of describing it.

Say for example, the 0W-20 was blended with 4cSt base oils while the 5W-20 was blended with 4 and 6cSt base oils. Both are using SK's Yubase for example, so they are using the same family of base oils, but the 0W-20, to hit the 0W-xx Winter rating, has a lighter blend.

For API SP it's D6335 (Teost 33c), and it allows up to 30 mg. 0W-20 oils are exempt from this test.
The reason for the exemption being the high moly content in some Japanese 0W-20 oils and TEOST 33C not liking moly. Nevertheless, TEOST 33C has been shown to be a useless test to determine real-life coking, but it has still managed to stay in ILSAC because it is cheap to perform. However, it's probably even less useful than the Russian oil-scorching test.

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.
OK, think we are mostly on the same page with regards to the caveats. The PD pump will, assuming we aren't on the relief, get oil to anywhere pressure lubed at roughly the same time, I think @Shannow posted a study from the SAE that showed full envelopment time between different oils at different temperatures. However, the places I mentioned, like the pistons and cylinder walls that are splash/spray lubricated, will receive lubrication sooner/receive better lubrication with an oil with a better Winter rating.

This won't change the time it takes for the AW additives to activate, so wear is elevated until they are, hence the claims about start-up (warm-up) wear.
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.
Would depend on the relief pressure set on the pump and whether we are hitting it, so there are some variables we need to account for here. I believe you and Zee covered that in your discussion already however.
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.
Yes, I'd agree with that. It isn't about oil pump or system volume at these locations but how effectively oil can be sprayed/cast on them, where a better Winter rating can provide better lubrication faster.
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.
Yes, pre-lubers ensure that there's oil in locations it needs to be to reduce reliance on existing AW coating build-up, potential removal of, and subsequent wear, while lubricant AW chemistry is not yet active. Wear is still elevated, but it is reduced. This can be improved further by ensuring that the lubricant is also pre-heated, which we also see in some applications.
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.
Yes it is, lol, but I sense that it needed to be mentioned given the direction this conversation has gone, lol.
So to my original statement - 0w20 does everything 5w20, but it does it better.

Edit:

I messed up the quotes somehow.

Since we are calling out caveats and have covered the start-up/warm-up wear ones, we should also consider what using lighter base oils means at the other end of the spectrum. Assuming the same family of base oils being used for both products, the 0W-20 is going to have a lighter base oil blend, which means a higher Noack, higher VII content and higher likelihood of experiencing mechanical shear. Depending on the application, this may also increase the likelihood of ring land area deposits (thinking of the Thin Film Oxidation Test and Sequence IIIG or its successors for example). Of course some manufacturers change-up the base oil blend when going with the a 0W-xx. Mobil has a history of using PAO, in varying quantities, when producing these for example.

I apologize in advance for taking this subject even more into the nuance, but member @Gokhan has produced a calculator where he calculates base oil viscosity and "full shear" viscosity as well as VII concentration:

It's an interesting exercise, though one has to keep in mind that these are estimates.

Great discussion so far! Appreciate the engagement.

As you said, we’re getting into a lot of conversations that are significantly off point. And, if you want to have them - I’d probably prefer to have them over a beer (or a bourbon) and a cigar with you.
Yes, these are probably easier conversations to have in person, but I really appreciate the effort both of you have put in thus far. While we've wandered a bit OT, these are the sorts of "meat and potatoes" discussions I like to read/have on BITOG.
In my professional opinion, a well formulated 0w20, will be better than a 5w20. In this case, I believe this is the case when comparing two Warren products. As I know the base oils and their primary additive supplier for PCEO products.
I've made the same argument, though not using the same points and not using Warren products. Mobil was using considerable PAO in their 0W-xx oils, particularly their 0W-20 up until the most recent revision, while the 5W-20's were Group III based.
That being said, I’m going to head to bed. It was a good debate, and I hopefully linked some good articles.
My apologies, but I had gone to bed after tagging @ZeeOSix and didn't see the subsequent discussion until now. I appreciate the debate and it went the direction I had hoped it would.
To the previously mentioned thick vs thin, and boundaries of lubricants - I did find the slides of the article. But not the full paper. Warning - pdf

It’s a fun read if you’re into that thing.

STLE has some amazing resources. While it’s not 0w20 vs 5w20 tests, that are easy to understand. It’s concepts that you can take, then apply elsewhere.
I'll give that a read in a bit here.

The reason for the exemption being the high moly content in some Japanese 0W-20 oils and TEOST 33C not liking moly. Nevertheless, TEOST 33C has been shown to be a useless test to determine real-life coking, but it has still managed to stay in ILSAC because it is cheap to perform. However, it's probably even less useful than the Russian oil-scorching test.

Right. Teost has shown to not be directly correlative to engine deposits. I'm glad that it's starting to fall out of favor. That said, there are some conclusions we can draw from Teost when compared with other tests.

Anti-oxidants and dispersants can reduce deposit formation, but it relies on low volatility base oils. From STLE...

"High-Temperature Bench Deposit Tests (TEOST MHT and 33 C) yields better results if high-quality, lower-volatility base oils are used in combination with good dispersants and antioxidants. Some molybdenum-based friction modifiers might be problematic in the 33 C, potentially excluding some good fuel economy chemistry."

STLE Webinar - Component Performance in Engine Oil Formulation

Right. Teost has shown to not be directly correlative to engine deposits. I'm glad that it's starting to fall out of favor. That said, there are some conclusions we can draw from Teost when compared with other tests.

Anti-oxidants and dispersants can reduce deposit formation, but it relies on low volatility base oils. From STLE...

"High-Temperature Bench Deposit Tests (TEOST MHT and 33 C) yields better results if high-quality, lower-volatility base oils are used in combination with good dispersants and antioxidants. Some molybdenum-based friction modifiers might be problematic in the 33 C, potentially excluding some good fuel economy chemistry."

STLE Webinar - Component Performance in Engine Oil Formulation
I would change "lower-volatility" with "higher-base-oil-quality". For example, an XOM SpectraSyn 4 PAO with a higher Noack should perform equally or better (probably better because it is thinner and thus has a lower aniline point (better solvency)) than an XOM SpectraSyn 6 PAO with a lower Noack., contradicting the authors' conclusions above.

OK, think we are mostly on the same page with regards to the caveats. The PD pump will, assuming we aren't on the relief, get oil to anywhere pressure lubed at roughly the same time, I think @Shannow posted a study from the SAE that showed full envelopment time between different oils at different temperatures. However, the places I mentioned, like the pistons and cylinder walls that are splash/spray lubricated, will receive lubrication sooner/receive better lubrication with an oil with a better Winter rating.

This won't change the time it takes for the AW additives to activate, so wear is elevated until they are, hence the claims about start-up (warm-up) wear.

Would depend on the relief pressure set on the pump and whether we are hitting it, so there are some variables we need to account for here. I believe you and Zee covered that in your discussion already however.

Yes, I'd agree with that. It isn't about oil pump or system volume at these locations but how effectively oil can be sprayed/cast on them, where a better Winter rating can provide better lubrication faster.

Yes, pre-lubers ensure that there's oil in locations it needs to be to reduce reliance on existing AW coating build-up, potential removal of, and subsequent wear, while lubricant AW chemistry is not yet active. Wear is still elevated, but it is reduced. This can be improved further by ensuring that the lubricant is also pre-heated, which we also see in some applications.

Yes it is, lol, but I sense that it needed to be mentioned given the direction this conversation has gone, lol.

Since we are calling out caveats and have covered the start-up/warm-up wear ones, we should also consider what using lighter base oils means at the other end of the spectrum. Assuming the same family of base oils being used for both products, the 0W-20 is going to have a lighter base oil blend, which means a higher Noack, higher VII content and higher likelihood of experiencing mechanical shear. Depending on the application, this may also increase the likelihood of ring land area deposits (thinking of the Thin Film Oxidation Test and Sequence IIIG or its successors for example). Of course some manufacturers change-up the base oil blend when going with the a 0W-xx. Mobil has a history of using PAO, in varying quantities, when producing these for example.

I apologize in advance for taking this subject even more into the nuance, but member @Gokhan has produced a calculator where he calculates base oil viscosity and "full shear" viscosity as well as VII concentration:

It's an interesting exercise, though one has to keep in mind that these are estimates.

Great discussion so far! Appreciate the engagement.

I am not spending nearly as much time on BITOG anymore. Would you like to become an administrator for my HTFS sheet so that you can include more oils and update it?