I have been using syth now for over 2 years in my car. I understand some of the basic basics but I am a bit lost when it comes to polyalphaolefin, (PAO) (class IV) and Ester (class V) based products. What is the difference, what does it mean for the engine if I use an ester based or polyalphaolefin based synthetic?

Here is an oil guide for people to look at who don't understand my questions.

http://www.trustmymechanic.com/motor-oil-bible.pdf

http://shogunoil.com/Shogun_leaflet.pdf