V8 Engine Tech (L76/LS3)
It's something like this.
5w-30 = 5w cold then goes to full 30
It has some principle name I just don't remember.
If the oil is a single number like 30,40,50sae then it starts at cold thicker then a conventional 5w-, 10w-, 15w- etc.
Think of it this way first number is cold and second is hot.