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Those grades are actually SAE viscosity indices. Here's a graph of some of the indices.

View attachment 1058584

A multi-viscosity rating (e.g. 5W-30) means that the oil's viscosity chart is just below the SAE 5 line at 32F/0C, and above the SAE 30 line at 212F/100C. Here's a chart of an oil's viscosity that just meets the rating of a SAE 5W-40. If an oil's viscosity is between the 0W and 5W line at 32F/0C, it's called a SAE 5W oil. If the oil's viscosity is anywhere between the 30 and 40 line at 212F/100C, it's called a SAE 30 oil.

View attachment 1058585

The SAE viscosity indices are based on a simple test of draining oil out of a container through a tube and timing how long it takes to drain out. There are more important tests of how the oil physically behaves in actual operation. The big one is the high-temperature, high-shear (HTHS) test. The BMW LL-01 requires a HTHS viscosity of 3.5 cP or greater, as does the ACEA A3 B4 specification. But, the BMW LL-01FE (a SAE 0W-30) only requires a HTHS viscosity of 3.0 cP. or greater.

Here's a data screen from the Lubrizol website. Lubrizol is the industry leader in lubricant and fuel additives.

View attachment 1058588

When BMW's spec's their BMW LL-01 oil, they call for it to be an SAE 5W-30, but with a relatively high HTHS viscosity. But, it's SAE viscosity index at 212F/100C is real close to but just below the SAE 40 line. It's probably easier to make a BMW LL-01 oil that's just above the SAE 40 line at 212F/100C. So, that's what Shell, Castrol, Motul, etc. do. Similarly, some oils that meet BMW LL-01 have a SAE viscosity at 32F/0C that's below the SAE 0W line, allowing them to be labeled as a SAE 0W-40 instead of a SAE 5W-40.
There are several “but’s” here:

1. Multigrade oils winter rating, 0W, 5W etc. is determined through Cold Cranking Simulation as part of J300 requirement:


2. BMW LL01 FE is requiring HTHS of minimum 3, and maximum 3.5. It can be 0W30 or 5W30. BMW TPT 0W30 that is LL01 FE has HTHS 3.1cP. Motul Specific 5W30 LL01 FE has HTHS 3.4cP. It is oil designed for fuel economy.

3. LL01 since 2018 doesn’t recognize anymore 0W30 and 0W40 because of OCI requirements of B generation engines. Since high HTHS oils in that grade oxidize more, they can’t meet those OCI requirements. So BMW eliminated them.

4. Generally, 5W40 oil is cheaper to make. But not for European vehicles. Problem is very tough requirements behind MB229.5 and MB229.51/52 approvals, mostly evaporation loss of max. 10% and deposits. All things being equal (base stocks, polymers etc. ) the more spread between XW and XX, the more volatility there is. Good example are Castrol Edge 0W30 and Edge 0W40. Basically those are same oils in foundation. But 0W30 has evaporation loss of 8.1% while 0W40 has 9.1%. The reason are Viscosity modifiers. But that is actually exceptional result for 0W40 oil.
Edge 5W30 A3 and 5W40 A3 have evaporation loss (Noack) 9.1% and 10%. These two oils have same foundation. Why higher Noack in oils that have lower spread between numbers?
Castrol in 0W30/40 oils uses PAO base stocks and star polymers. It is their premiere product. Their 5W30/40 use Hydrocracked base stocks and chain polymers, therefore higher volatility. 5W40 is just on border meeting MB229.5 requirements. How? Well they thinned last year this Edge and made it almost 5W30. KV100 of 5W30 is 12.2, while KV100 of 5W40 is 12.8. Cut off between 30 and 40 is 12.5cst. Before, 5W40 had KV100 of 13.9, and because of cheap base stocks and chain polymers, it was too volatile to be approved for MB229.5, so it only had MB229.3 approval. So instead of using bit of PAO and star polymers, they used less viscosity modifiers and achieved lower volatility using cheaper method.
They could bring 5W40 from Europe, but profit margin would be lower.
So basically, Castrol Edge 5W40 is mire or less, 5W30. Especially when taken into consideration mediocre HTHS of 3.6 which for that grade indicates, again, cheap base stocks.
Bottom line: Castrol Edge 5W30/40 A3, and Castrol Edge 0W30/40 A3, are completely different oils!


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I went and dig out PDS of Pennzoil and Quaker State:

Quaker State 5W40:

Pennzoil Platinum 5W40:

So, if you take a look you will see that basically, those two oils are absolutely the same.
Pennzoil has an additional flashpoint test listed which might be just a fluke on whoever did PDS or attempted to distinguish two PDS.
Also, QS has pour point listed as -39. That could be the minimum required pour point, while Pennzoil PDS has an actual pour point.
However, based on other data, these two oils are absolutely identical.
 

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Don’t be too sad. Some of the Mobil 1s are quite high in additives, which tend to increase CBU. I picked the 5w-40 Euro for use in my ACVW simply because it had the highest ZDDP of any quality oil I could find, either 1200-1300 ppm IIRC. A single jug lasts me two full oil changes. :)


Via the interwebs
^This.
In N55 QS is better choice. Actually any LL01 is better choice as SAPS is lower. Excellent oil for N51/52. It basically has all ingredients of racing oils without claiming to be that. If Liqui Moly could make oil like that, they would market shit out of it.


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