B58, you bring up some good points about what qualifies as "synthetic". We have a retired Mobil engineer guy in our area that I've known for many years. I'd classify him as a straight-shooter, and here's what he said. Mobil's technique for their synthetic is to manipulate dino oil at the molecule level by truly changing the molecule chains into the best possible designs to provide all the benefits that one can get out of a motor oil. This process is supposed to be about as complicated as making true synthetic oil out of other materials, and the benefits are supposed to be the same. Of course, there's also magic to be had in the types of additives and such that are added to an oil, and Mobil is supposed to excell at this. Now, I'm not necessarily a "Mobil 1 only" type of guy, as I think most quality brand oils out there meet all the minimum requirements that most of our automotive and motorcycle engines need. Still, if standard dino oil molecules are highly manipulated to the degree that my acquaintance suggests they are, then I'd tend to classify that as true synthetic. He did, however, state that Mobil 1 has some blends that are just that...blends of good dino oil and manipulated molecule dino oil that they've started marketing in the last few years. He said this bothers him that they still try to classify these blends as synthetic.

 

TNC, yep, that manipulation of the petroleum oil is the "severely hydrocracking" process I mentioned. The resultant base molecule (aka, Group III Petroleum) is so close to man-made-in-the-lab base molecules, there are often only very miniscule differences....EXCEPT, the petroleum products are much cheaper to refine that beginning from scratch in a lab!

You also hit on an excellent point: once a base molecule is established, it's the balance of the additive pack that really makes one oil perform better than other oils. Mobil 1 has an excellent reputation for putting out good products.