The Groups are:
- Group I - Crude oil, totally mineral base, simple refining method. Still contains waxes and other contaminants.
- Group II - Crude oil again, but more advance refining methods to improve its qualities. A very small percentage of wax remaining.
- Group III - This group is an advanced Group II; It has all of its waxes and contaminants removed and been further refined by a process called 'Hydrocracking' (Commonly called Synthetic)
- Group IV - POA or Poly-Alpha Olefines. This is not Crude oil based and is a true synthetic.
- Group V - Esters. There are countless Esters available, all with similar qualities. This group is the most advanced method of creating and refining synthetic lubricant stocks.
Pictures make it so much easier to understand.
The Neopoly Esters shown are an example of 2 different processes for the one material and the gain that can be achieved.
The higher up the group is, the more expensive it is to produce.
If you are buying synthetic oil and the oil you are getting is marked HC/MC or VHVI/XHVI then it is a Group III "Synthetic" and not a true Group IV or V Synthetic. It really does make all the difference.