0W20 and 5W20?

[mrcoolguy]

I have been comparing 0W20 specs to 5W20 oils. What makes a 0W20?
I see Pennzoil Ultra's 5W20 is 47.43 @ 40 degrees celsius and 8.4 @ 100 degrees celsius... this is very similar to Amsoil's 0W20 at 46.7 degrees celsius @40 degrees and 8.8 @ 100 degrees celsius. Pour points are also very similar. So does this oil technically qualify as a 0W20 in sense? I am just confused. I appreciate the help.

 

[fsskier]

Well of course 40C is still pretty hot....104f....so they should be close at that temperature.

Look at the CCS numbers....at - 35C and you will find they are greatly different.
Usually the number published for 5Wxxx is done at -35, for 0Wxx it might be at -40.
For those of us that use F a lot, that is 9 degrees colder.
Often the 0W is thinner at -40 than the 5 w is at -35.

Now for those of us that were in central Wisconsin last weekend - -20 f.... that makes a difference.

Those living somewhere that thinks 104f is a cold start will not likely need it!

 

[Garak]

It has to do with the cold cranking specifications. A 5w-20 and a 0w-20 can be pretty much the same under normal conditions. Anything before the "w" is for cold cranking, which is measured at temperatures you will never experience in LA, but I am experiencing right now.

 

[ARCOgraphite]

Mrcool:
Any oil thet meets the 0w rating HAS TO BE rated 0w it is not a "marketing" option. No need for the 0w where you live unless it buys you a better oil formulation. I love to see a 0C kv typical data required by API/ILSAC, but you can extrapolate the expected data point from the upper and lower KV #s and/or the VI if provided. No Substitute for actual data points as the newer VII chemistry may behave unexpectedly.

 

[Samilcar]

The "W" rating prefix (Winter rating) just tells you how the oil performs at the sub-zero temperature at which the winter rating test is performed. Often times the viscosity of 0W-20 and 5W-20 oils are identical from 32°F and higher.