VW Oil Specifications

Just wondering if anyone can actually explain what the various VW oil specs such as VW 504 00 actually are. What do the numers actually
Can these specifications be obtained on the internet? How do we know which oil is a better specification from these numbers?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.