Okay ..I was never a good texted based student. The lecture(r) was my principle tool for learning. I don't integrate some things well and need to apply appropriate "analogs" for assimilation. Here I need to get a grip on the oil groups. Group I appears to be normally refined oil. Group II appears to use a catalyst to reform the moledules. There also appears to be a "II+" element to this group. Group III is allegedly an advancement or further extension of this catalytic process (some said longer and hotter). Group IV - never really mentioned much so I haven't a clue. Group V - allegedly used for additives = why? Too expensive to produce as a stand alone lubricant? Unsuitable for use as one? So ..I've seen threads that claim that Group II base stocks are superior to Group III ..yet I also hear exactly the opposite. Here a Group II gets a thumbs up over a Group III diesel oil. So I guess the Group III diesel oil producer just spent all the extra catalyst time to detune their oil down to below the inherant properties of the, in this thread, superior Group II base stocks. As you'll also see in this thread ..the Group II is referred to as a PAO ...which everyone appears to hail as the greatest thing in the world ...on the other hand ..in another thread "Mobil I is rumored to be Group III" and it implies that the Group III is NOT PAO. So someone also, in this case, and for no apparent reason "detuned" their oil by spending too much time in the catalyst (using the advanced process) to escape the comfort of PAO and evolve it into an inferior product which you all critique. What is wrong with this picture??? Now I don't learn at a rapid rate ...but someone here has to admit that there are a whole lot apparent conflicts in this "Group heirarchy" that don't follow normal, sensible, rational. To index "me" ..I can understand "mesh currents", "high Z", harmonics, and a host of other various complex processes and functions ..but this "groupese" just isn't falling into any sound rationale~. Can any of you true oil geeks explain this lack of apparent sensibility ..or rather provide me with the "special education" to align this mess into order? btw- I've asked for this several times ...and although I've gotten some "skinny" answers to specific elements ..no one appears to want to tackle this. Links to other vendor sites only appear to add more conflict.