SAE 26

[Solarent]

PC-11 Team is debating how to differentiate new fuel economy oils for diesels which will replace the XW30 diesel, and keep them separate from the current 15W40 while still maintaining the same API Diesel Code (likely to be CK-4).

It was proposed that a new SAE grade for diesels (SAE 26) be used. This would be similar to the approach for new SAE 16 grade oils for gasoline engines.

Sounds to me like the J300 is going to get more complicated - again.

Link

Originally Posted By: FROM THE ARTICLE
The New Category Development Team took up this discussion at their Jan. 30 meeting. There seems to be little debate that PC-11A will continue to have a minimum 3.5 cPs HTHS viscosity limit, as is the case with CJ-4 and earlier oil categories. This provides the needed backwards compatibility for existing engines in on- and off-road applications. However, there is a recognition that SAE XW-30 oils should provide fuel economy benefits versus SAE 15w40, and engine builders want to wring as much fuel economy as they can from the new oils.

Hence, for PC-11B the goal is to gain fuel economy without sacrificing engine durability. One way to achieve this, the meeting heard, may be with a new viscosity grade tentatively referred to as “SAE 26,” which would be defined using either HTHS viscosity between 2.9 and 3.2 cPs or by kinematic viscosity of 9.3 to 10.5 cSt at 100 degrees C. This might result in a more limited backwards compatibility which would be OEM, engine and application dependent. Pursuing this idea will also require drafting a formal proposal to SAE to amend its engine oil viscosity classification system, SAE J300. This issue should go to API’s Lubricants Group for action, the development team decided.

 

[CATERHAM]

Yes unduly complicated, and indicative of as committee designed solution, IMO.
So the SAE grade 26 with a HTHSV between 2.9cP and 3.2cP will represent what we usually referred to as a "light 30 grade".
The problem is that the number 26 would seem to suggest a heavy 20 grade oil which of course it's not.

Why they just can't use the actual viscosity measure as the label is beyond me, instead of a number that represents another range of numbers. Just put 2.9-3.2 on the bottle label, but I guess that would be too simple.

 

[Garak]

I would assume for the heavy duty diesels, those in charge of maintenance would be paying attention to builder approvals and the viscosity, in any case.

 

[Solarent]

Originally Posted By: CATERHAM
Why they just can't use the actual viscosity measure as the label is beyond me, instead of a number that represents another range of numbers. Just put 2.9-3.2 on the bottle label, but I guess that would be too simple.


I agree, that probably would be simpler.

There is also the crossover between diesel oils and gasoline oils to worry about too. It seems that there will be more distinction between the two in the future which is probably good. However the average consumer who knows nothing about oils is probably going to get confused.

 

[Shannow]

If they did that, then people would start with the arguments that engines don't run at 150C, and that an oil with an HTHS of 2.6 at 80 degrees is the same as a 3.5 at 100C...and all the other shenanigans...

 

[CATERHAM]

Originally Posted By: Shannow
If they did that, then people would start with the arguments that engines don't run at 150C, and that an oil with an HTHS of 2.6 at 80 degrees is the same as a 3.5 at 100C...and all the other shenanigans...

And would be that be a bad thing? It's how you learn.

 

[Shannow]

It's fine, as long as appropriate and meaningful...

things like "Porsche backspecced to 3.5 for all cars produced in the last 30 years so Motorcraft 2.6 is fine for your GM truck or M5" is neither logic nor learning.

 

[A_Harman]

Why not classify oils based on HTHS at 100C?
This would be most relevant for fuel consumption for everyday people running everyday duty cycles.
The patchwork of kinematic viscosity grades is getting too confusing.

I've been thinking for some time that the HTHS grades are too close together. For instance, there is 2.3, 2.6, 2.9, then 3.5 and above. Why not break it into larger increments, such as 20%:

2.0, 2.4, 2.9, 3.5, 4.2, 5.0