As I recall from my days in schooling as an aircraft mechanic, parrafinic crudes originated in the eastern parts of the the US. Pennsylvania, I think, was the first state to produce parrafinic crudes and they are  particularly sooty.  As I recall, an example of a commercial refined oil from a parrafinic crude would be Quakerstate Motor Oil. Napthenic crudes came from the more western states...Oklahoma, Texas, etc. as well as western provinces of Canada and contain quite a bit of sulfur that has to be dealt with in refining. In my flying career days, often I would fly over refining plants in western Canada,  and beside the plants would be enormous piles of sulfur. Exxon oils would be an example motor oils from napthenic crudes.

Use of top quality refined and blended oils from one or the other of these crudes won't make much difference in performance in todays modern engines, but emissions could be an issue. Each has it's own problems in that area, with western crudes tending to produce products that lean in the direction of putting sulfur based compounds into the air which can eventually result in acid rain. I don't remember about the parrafinic crudes, but there are pollutants that derive from their use.

In the earlier days of the oil boom and industrialization of America, not oils were imported. America's oild fields were discovered and developed. But in modern times our oils come from around the world, and oil blends reign supreme.

In my opinion, if you use one of todays modern high performance blended motor oils, you will generally get good service with them. Much research and development has gone into producing modern motor oils for todays high performance engines. The trick today is to select a top rated oil, and stay with it through the life of the engine, paying close attention to maintaining proper oil levels and maintenance cycles.,ie, oil changes and new oil filters at the proper times. These oils are blended to give the best molecular structure for the job....not breaking down in high heat, not being to resistant to movement in severe cold. The length  of the molecular chains that make up the oil becomes important ...to short, and the oil doesn't cling and lubricate. To long, and it becomes sticky/gooey and doesn't lube but clogs things up. Over time the long chains are broken up and the lubrication qualities are lost. This is one reason there is a move to synthetics. They last longer.

John Rodgers
 
 

Tromper wrote:

O.K. I've seen a reference to parrafin oils, and now napthenic, or somesuch, oils. How many different types, and what's the advantage to vehicle with a high soot output??? JT82 Diesel "Manatee"