Automotive technology has changed drastically since the 60s to meet automotive requirements. Government mandates concerning nitrous oxides, particulates, fuel economy and removal of environmentally hazardous additives as well as changes in automotive technology, have had significant impacts on engine oil.


The current American Petroleum Institute (API) automotive oil classification is SN Plus ("S" stands for spark ignition and the "N" represents next oil category). This represents lower viscosity higher heat resistant engine oils that meet an exhaustive battery of lab and field engine tests. To certify for SN Plus, if a major oil company, the cost is $2+ million dollars. Not the old days!

85% prox. of finished engine oil is base oil. Base oils are categorized in 4 groups - Group I, Group II, Group III & Group VI.

	Group I	- Generally SX (solvent extracted) type base oils. Still today make up a majority of base oil production. They are the base of many engine oil brands. With additive chemistry they provide good protection to our MGs.
	Group II	- These base oils go thru a hydrogenation process which reduces aromatics and so provide higher oxidation stability. There's extra oxidation protection at higher temps & low cost. Chevron is basic in this technology.
	Group III	- In North America Group III base oil can be considered a synthetic although this is not case in Europe. Group III base oils approach a common hydrocarbon molecular structure similar (but not equal to) to Group IV PAO (poly-ala-olefin) and do provide better oxidation/cold climate engine protection at a cost less than a synthetic. The lower cost is the result of process vs. catalytic treatment which also produces higher yields. Shell uses gas-to-liquids technology and sells it as a synthetic.
	Group IV	- A PAO synthetic starts out from the same crude barrel as any other base oil. I have heard that they are not considered petroleum product but in fact they are. A PAO synthetic base oil uses process & catalysts to remove heavy hydrocarbon molecules that are waxy and flow poorly at low temps, but also light molecules that tend to agitate & oxidize (turn the oil black) at high temps. A finished hydrocarbon structure represented by molecules of the same size will behave

Continued on page 9)