If you look at the CCS viscosity (ASTM D 2602) of Amsoil ATO 0W-30 on Amsoil's web site it reads 5520 !!! That surely should be 2520 I assume .......... 5W-30 ASL has 2555 ..... and 10W-30 ATM has 3444
Current specs for the 10w-30 on the new sheet I have show vis @ -25C is 3097 Cp. The spec sheet for the 0w-30 is up to date, but the one for the 5w-30 has not been updated. It still shows the CCS viscosity tested @ -25C, when it should be -30C ....I'd estimate vis @ -30C for the 5w-30 to be approx 3800 Cp, based on the old data.
For a PAO based synthetic, the general rule is that the CCS viscosity will increase by a factor of 1.7 for every 5C drop in temp. This allows you to convert viscosities to different temps. For a petroleum oil, you multiply by a factor of 2.0 for every 5C drop in temp.
ASTM D2602 is the old name for the ASTM D5293 test protocol - they are exactly the same test....
The standard, CCS test temps did change, when the "SAE J-300" standard was revised (in June of 2001, as I recall). At that time, the standard test temps for all SAE grades was lowered by 5C, and the max viscosity allowable changed from 3500 Cp in most cases to 6200-7000 Cp, depending on SAE grade. For example, max allowable for 0w-xx oils is 6200 Cp @ -35C ...for 10w-xx oils is 7000 Cp @ -25C.
Oil specs are jointly developed by a group composed of the API, the SAE and the ASTM.
API = American Petroleum Institute
SAE = Society of Automotive Engineers
ASTM = American Society for Testing and Materials
ACEA = Euro version of API (formerly CCMC)
DIN = Euro version of ASTM