Relationship between winter viscosity and pour point?

[Avery4]

Hello everyone, I recently noticed something strange that got me thinking about how the winter viscosity of oils (the first number before the W) relates to an oil's pour point. I have always assumed (and generally noticed) that oils with a lower cold viscosity tend to have lower pour points assuming the same brand and product line, which made sense. However, when I was looking at the specs for Mobil 1 Extended Performance recently, I noticed that their 5W30 has a significantly worse pour point than their 10W30 and their 0W20 has a slightly worse pour point than their 5W20. I asked Mobil about why this is, but I didn't get a useful answer. https://www.mobil.com/en/lubricants...s/products/mobil-1-extended-performance-5w-20

Similarly, I also noticed that many 10W oils have significantly better pour points than some 0W oils. For example, Amsoil Signature Series 10W30 has a pour point of -52 degrees F while Mobil 1 Advanced Fuel Economy 0W30 has a pour point of -43 degrees F. If anything, shouldn't an oil with a 0W rating have a lower pour point than a 10W rated oil?

To be clear, I'm not singling out or bashing Mobil as I like their products and I have seen this with other manufacturers too, I'm just using them as an example since their specs show this well.

Anyways, I'm just curious why this may be and whether the pour point or the winter viscosity rating is a more useful indication of an oil's cold weather performance since I haven't seen this discussed before.

 

[PWMDMD]

My limited understanding is pour point is a poor proxy for cold weather performance because during start-up the engine does not pour the oil - it pumps the oil - and the relationship between pourability and pumpability is not well defined/consistent. To get around this, there are tests that are designed to measure pumpability of cold oil.

 

[OVERKILL]

Hello everyone, I recently noticed something strange that got me thinking about how the winter viscosity of oils (the first number before the W) relates to an oil's pour point. I have always assumed (and generally noticed) that oils with a lower cold viscosity tend to have lower pour points assuming the same brand and product line, which made sense. However, when I was looking at the specs for Mobil 1 Extended Performance recently, I noticed that their 5W30 has a significantly worse pour point than their 10W30 and their 0W20 has a slightly worse pour point than their 5W20. I asked Mobil about why this is, but I didn't get a useful answer. https://www.mobil.com/en/lubricants...s/products/mobil-1-extended-performance-5w-20

Similarly, I also noticed that many 10W oils have significantly better pour points than some 0W oils. For example, Amsoil Signature Series 10W30 has a pour point of -52 degrees F while Mobil 1 Advanced Fuel Economy 0W30 has a pour point of -43 degrees F. If anything, shouldn't an oil with a 0W rating have a lower pour point than a 10W rated oil?

To be clear, I'm not singling out or bashing Mobil as I like their products and I have seen this with other manufacturers too, I'm just using them as an example since their specs show this well.

Anyways, I'm just curious why this may be and whether the pour point or the winter viscosity rating is a more useful indication of an oil's cold weather performance since I haven't seen this discussed before.

Pour Point was abandoned as part of J300 for determining the Winter grade precisely because it was wildly inaccurate at predicting cold performance. This is why we have CCS and MRV.

Also, those Mobil PDS figures may be reversed.

 

[IndyIan]

Pour Point was abandoned as part of J300 for determining the Winter grade precisely because it was wildly inaccurate at predicting cold performance. This is why we have CCS and MRV.

Also, those Mobil PDS figures may be reversed.

They do seem a bit off for the same product line? Usually they kind of line up like you would think they would.

 

[OVERKILL]

They do seem a bit off for the same product line? Usually they kind of line up like you would think they would.

Yup, I think they have the intern doing the website updates.

 

[Avery4]

Good point about pour point and and pumpability being different, I just assumed they would be closely related.

I thought about the possibility of the specs being reversed too, but it seems like Mobil acknowledged that the specs didn't make sense.

Here was their first response: "Thanks for writing to us. While I normally see lower pour points with lower W grades, and higher W grades, the specs can vary from one formulation to the next. I'm copying our Technical Support Center for assistance."

Then their technical support center responded and said "
As Jim from Mobil 1 team says, the pour points for the different SAE grade oils may vary depending upon its formulation.
So we would recommend to follow the manufacturer recommended SAE Grades for appropriate operating temperatures and would recommend not to rely on the pour points as it is far below almost any operational need for most customers."

 

[PimTac]

If I recall correctly those specs on the Mobil website have been like that for a while now. If so that is not a good showing on their part.

 

[benjy]

be sure to LOOK at the temp in the specs as they VARY + of course REAL synthetics are different as the Ams small engine advertised at 10-30 is actually a 30W PAO that meets the 10-30 spec!!

 

[OVERKILL]

Good point about pour point and and pumpability being different, I just assumed they would be closely related.

I thought about the possibility of the specs being reversed too, but it seems like Mobil acknowledged that the specs didn't make sense.

Here was their first response: "Thanks for writing to us. While I normally see lower pour points with lower W grades, and higher W grades, the specs can vary from one formulation to the next. I'm copying our Technical Support Center for assistance."

Then their technical support center responded and said "
As Jim from Mobil 1 team says, the pour points for the different SAE grade oils may vary depending upon its formulation.
So we would recommend to follow the manufacturer recommended SAE Grades for appropriate operating temperatures and would recommend not to rely on the pour points as it is far below almost any operational need for most customers."

Those are just CYA responses basically saying "we didn't look at it, but it might not be wrong blah blah blah"

 

[Avery4]

If I recall correctly those specs on the Mobil website have been like that for a while now. If so that is not a good showing on their part.

I don't know how long their website has been that way as I just noticed it a couple weeks ago, but I agree about it not looking good especially after at least one person brought it to their attention and they didn't correct it yet (if it's an error as we suspect).

Potential errors aside, a listed pour point of only -27 degrees F for their top of the line 5W30 oil sure doesn't look good, that's the worst I have seen in a while by a large margin and IMO a legitimate concern if someone believes it and lives somewhere cold.

 

[kschachn]

Potential errors aside, a listed pour point of only -27 degrees F for their top of the line 5W30 oil sure doesn't look good, that's the worst I have seen in a while by a large margin and IMO a legitimate concern if someone believes it and lives somewhere cold.

People should be looking at the winter rating printed on the container they are buying. The typical values on a PDS are not the definitive marker of cold-weather performance. The winter rating is.

 

[Avery4]

People should be looking at the winter rating printed on the container they are buying. The typical values on a PDS are not the definitive marker of cold-weather performance. The winter rating is.

Right, but regardless of whether their specs are correct or an error, it doesn't look good when the pour point is higher than the temperature a 5W oil's pumpability is tested at and close to or higher than the temperatures many people experience. Is it even possible for an oil that passed pumping tests at -31 degrees F to legitimately have a pour point of only -27 degrees F?

 

[Deleted member 89374]

People should be looking at the winter rating printed on the container they are buying. The typical values on a PDS are not the definitive marker of cold-weather performance. The winter rating is.

I saw this thread and immediately knew that if you're not already here, I'll definitely page you. It's all about pumbality, right? Also, PDS documents can have errors in them, not on purpose of course. So the winter rating it is, right?

 

[kschachn]

I saw this thread and immediately knew that if you're not already here, I'll definitely page you. It's all about pumbality, right? Also, PDS documents can have errors in them, not on purpose of course. So the winter rating it is, right?

Well if a blender doesn’t put a disclaimer on the PDS stating they are typical values and not guaranteed then they are taking a risk IMO. Now that isn’t saying that if they do choose to publish one that it shouldn’t be accurate. I am not saying that. However, those values are not the guaranteed performance of the oil. The SAE grade, the licenses and the approvals are the guarantees. If those are wrong then I would agree it is a legitimate concern. On a PDS? Not so much.

 

[Deleted member 89374]

Well if a blender doesn’t put a disclaimer on the PDS stating they are typical values and not guaranteed then they are taking a risk IMO. Now that isn’t saying that if they do choose to publish one that it shouldn’t be accurate. I am not saying that. However, those values are not the guaranteed performance of the oil. The SAE grade, the licenses and the approvals are the guarantees. If those are wrong then I would agree it is a legitimate concern. On a PDS? Not so much.

Very well said. I'm guilty of obsessing with the pour point as well. I no longer do so, however it took some reading to get here.

As a hobbyist, at least for me, when I started to look at PDS documents, it was like the "lubricant olympics". It's wrong though, so... so... wrong to do that and I guarantee that those who pick their oils solely based on PDS values won't necessarily be happy with the results.

I mean, if you live in Florida, or even in NC, like me, you don't need 0W-anything, unless you want to stick to the manufacturer's recommendation. However, there is nothing stopping someone from running a 5W-20 or even a 10W-20 in an engine calling for 0W-20.

 

[Jackson_Slugger]

They do seem a bit off for the same product line? Usually they kind of line up like you would think they would.

Yeah. The previous PDS for M1 5W-20 listing its pour point as -51, now it's -39 and both were SP rated...

 

[Deleted member 89374]

Yeah. The previous PDS for M1 5W-20 listing its pour point as -51, now it's -39 and both were SP rated...

It doesn't matter, as it has no obligation to be pumpable beyond -30C. Mobil changed the formulation when they went to Dexos 1 Gen 3. It's largely an improvement over the old formulation. The pour point is dictated by the base oils, co-base, and the additive package. When a blender formulates a lubricant, they don't aim to compete in the "Olympics for The Best PDS Numbers". They want to blend the best product they can with the resources they have at their disposal.

 

[Greasymechtech]

 

[Jackson_Slugger]

It doesn't matter, as it has no obligation to be pumpable beyond -30C. Mobil changed the formulation when they went to Dexos 1 Gen 3. It's largely an improvement over the old formulation. The pour point is dictated by the base oils, co-base, and the additive package. When a blender formulates a lubricant, they don't aim to compete in the "Olympics for The Best PDS Numbers". They want to blend the best product they can with the resources they have at their disposal.

That may be, but I doubt a lot of Mobil PDS are fully accurate and there seems to be some random sloppiness....

 

[Deleted member 89374]

That may be, but I doubt a lot of Mobil PDS are fully accurate and there seems to be some random sloppiness....

You're absolutely right, their PDS documents are not accurate, and their website leaves a lot to be desired for such a gigantic corporation. Their MSDS documentation is on point do, for the information that they're willing to disclose in it as far as typical properties are concerned.

This seems to be the norm these days. FWIW, Kendall and Shaffer Oil have the most accurate PDS documentation and websites. Ironically, Red Line, owned by P66, same parent as Kendall, doesn't. I actually asked RedLine several times, and they said they will eventually update their website... smh.