Thanks for the info Virtus. It is what the site linked to.
Gee whiz Castrol!
So that makes it really difficult to compare oils. Generally I see lower 40c viscosities for 0w vs 5w and that has always made sense to me until now 🙁
You are welcome, sir. The whole W thing was a mystery to me until I started poking around here and on other car sites.
Some companies make it so hard to find up to date information...I tend to find the lookup page for Shell/Pennzoil PDS hard to use, although the info is there somewhere. Easier for me to find Mobil 1 info, but they don't share a lot of details in general.
Amsoil's site is easy to navigate for me and shares a ton of info, but it's not enough for me to pony up the extra $$$ for the SS oils I find attractive.
The introduction of GM's dexos1 Gen 2 standard in 2017 has caused many SN/GF5 5W30s like the one you reference to be reformulated, so info from 2014 on that oil is almost certainly outdated.
I believe that 0W30 is generally referred to as "German Castrol" or GC on this and other sites and was a much sought after oil. As mentioned above, it seems to have become scarce in the US for whatever reason.
This site has good tables about what the numbers in an oil grade really mean;https://wiki.anton-paar.com/en/sae-viscosity-grades/
CCS is Cold Cranking Simulator and MRV is Mini Rotary Viscometer...the latter test is intended to measure how easy it is to pump a cold oil, the intent of CCS is pretty obvious.
It seems that the CCS spec is the more difficult one to meet for the oils we see on the shelves and the MRV spec is usually cleared by a wide margin when the results are shared.
Shannow, who works on lubrication issues in massive turbines IIRC, has proposed that a 2:1 ratio of MRV to CCS viscosity reflects an oil that has little to no Pour Point Depressant (PPD) added to it and has excellent "natural" cold weather properties, while a higher ratio reflects the use of PPD additives.