Actually, I thought Mobil 1 was one of the first Synthetics to switch away from being true synthetic (PAO) to highly processed dinosaur juice.
From your link above:
In the late 1990s, Castrol started selling an oil made from Group III base oil and called it SynTec Full Synthetic. Mobil sued Castrol, asserting that this oil was not synthetic, but simply a highly refined petroleum oil, and therefore it was false advertising to call it synthetic. In 1999, Mobil lost their lawsuit. It was decided that the word "synthetic" was a marketing term and referred to properties, not to production methods or ingredients. Castrol continues to make SynTec out of Group III base oils, that is highly purified mineral oil with most all of the cockroach bits removed.
Shortly after Mobil lost their lawsuit, most oil companies started reformulating their synthetic oils to use Group III base stocks instead of PAOs or diester stocks as their primary component. Most of the "synthetic oil" you can buy today is actually mostly made of this highly-distilled and purified dino-juice called Group III oil. Group III base oils cost about half as much as the synthetics. By using a blend of mostly Group III oils and a smaller amount of "true" synthetics, the oil companies can produce a product that has nearly the same properties as the "true" synthetics, and nearly the same cost as the Group III oil. The much more expensive traditional synthetics are now available in their pure forms only in more expensive and harder to obtain oils. To the best of my knowledge, Delvac-1, AMSOil, Redline, and Motul 5100 are the only oils made from pure traditional synthetics.
(Emphasis added) (Hey, he calls it dino-juice too! )
I have seen various claims about synthetic vs. regular oil. An article in the local newspaper stated a 20% improvement in fuel economy; it is also claimed that synthetic oil's change interval is twice that of regular oil (3000 vs. 6000?).
Do these claims hold water? Is synthetic oil worth the additional cost? Would it be worth my while to use it in my '92 VX? Let's face it. I'm such a miser that I'll try just about anything within reason to boost my fuel economy even further than my present 46-47 mpg (other than ridiculous infomercials ).
I run syn and a mopar factory filter in one vehicle With 4.500 - 5,000 mile change intervals. All other fluids (both diff's - t case and tranny are syn also from the factory). I changed the motor oil over to syn at about 9,800 miles after sufficient engine break-in. No noticable difference in gas mileage. I have used both Mobil 1 and Valvoline syn which are both brand names. The Valvoline is less than $20 for a 5 quart jug.
My other vehicle gets dino and a ac delco filter since the day it was new. (150,000 or so miles on it). It will keep getting dino. I usually buy quart bottles since it takes 4 1/2 quarts and the oil cost is somewhere around $12 or so depending which brand and if it is on sale or if I buy a case or what.
I always do my own maintenance - and there is not that much cost difference for whatever that is worth.
While I do believe that syn has superior lube qualities and less friction I really saw no difference in gas mileage.
Your results could vary, depending on the variables involved. This is just my experience with dino and syn.