Viscocity rating @ 40 C

[AEHaas]

Let me explain it for you.
As I leave my neighborhood I come immediately onto a highway with a lot of traffic moving at 55 - 70 MPH. I can wait for a period of time until you can pull out with very slow acceleration. It is what you must do if driving a Prius for example. Or you can pull up to the highway and just go by, as I say, gunning it. That means stepping on the gas and getting up to 60 or 70 MPH in like 2 or 3 seconds up to 9,000 RPM. 'Quite fun to do actually.

Ali

 

[weasley]

For me, the oil PDS (available to the public) would be more meaninful if it showd viscocity at "0"C or even "10" instead of 40

And what would you do with this information? Besides, if you're that interested and you know the viscosity at 40°C and at 100°C, you can calculate it at 0°C or 10°C or whatever you want.

 

[bonjo]

I got back my UOA results from millers and had a lond chat about it with the person who had done it.

Very helpful & knowledgeable. I also asked hime about the relevance of 40deg testing. Here is in short what he told me (hopefully I've got it right!):

• 40 deg viscosity is measured in industrial application and is of no relevance in automotive. For automotive application, the test is done @ 100deg.
• So depending on the application, they have two testing procedures He mentioned some labs only have one way of testing, to cover both application hence why we see 40deg
• In theory they should also test @ -35C to get the W (winter rating) of the oil. But explained used oil can/ does contaminate the instrument hence not done (I did not understand the full reason as it was getting too technical reason!).

So other than working out the VI as someone mentioned, there seems to be no point publishing it to the general consumer.
Now if oil companies could publish their -35degC viscosity, this would be interesting

 

[kschachn]

Now if oil companies could publish their -35degC viscosity, this would be interesting

However they do publish the oil’s winter rating.

 

[ZeeOSix]

So other than working out the VI as someone mentioned, there seems to be no point publishing it to the general consumer.
Now if oil companies could publish their -35degC viscosity, this would be interesting

Many oil makers show the CCS viscosity, which can be compared to the SAE J300 "W" rating grade to see where it falls inside the W grade range. For example, one 5W may test to have more CCS viscosity than another 5W at the same CCS test temperature.

 

[weasley]

I got back my UOA results from millers and had a lond chat about it with the person who had done it.

Very helpful & knowledgeable. I also asked hime about the relevance of 40deg testing. Here is in short what he told me (hopefully I've got it right!):

• 40 deg viscosity is measured in industrial application and is of no relevance in automotive. For automotive application, the test is done @ 100deg.
• So depending on the application, they have two testing procedures He mentioned some labs only have one way of testing, to cover both application hence why we see 40deg
• In theory they should also test @ -35C to get the W (winter rating) of the oil. But explained used oil can/ does contaminate the instrument hence not done (I did not understand the full reason as it was getting too technical reason!).

So other than working out the VI as someone mentioned, there seems to be no point publishing it to the general consumer.
Now if oil companies could publish their -35degC viscosity, this would be interesting

Although automotive engine oils are not classified by their kinematic viscosity at 40°C (KV40), it is used along with the KV100 to calculate the viscosity index (VI), which is often published on PDSs.

The cold cranking simulator (CCS) test which is run at cold temperatures to determine the 'W' number is not tested at a fixed temperature. The test temperature depends on what W rating the oil has. So a 0W-XX oil is tested at -35°C, 5W-XX oil is tested at -30°C, a 10W-XX is tested at -25°C and so on. And nobody, ever, tests used oils in the CCS - it is meaningless and problematic.

And oil companies do publish their CCS viscosities - I went to the first 0W-30 oil I thought of in the UK and found this:

 

[kschachn]

Yes another great conspiracy that well, isn't a conspiracy at all.

 

[bonjo]

good, comprehensive info weasley
Now I know how the CCS is tested with respect to the winter raring

must say the castro published spec you found is very comprehensive. You may find not all suppliers as forthvoming!

 

[KICK]

55 mph is gunning it?

I suspect he means he has to "gun it" to get to 55 mph quickly. FWIW the 40C measurement is pretty much useless, its just a test standard. Lube oils generally run hotter than the coolant temp on gasoline engines.