I think the MSDS may have been misread (the mentioned polyolefins apparently refer to a special additive). Generally "fully synthetic" means that besides the additives, which often come dissolved in "regular" mineral oils, the basestock is not a mineral base oil but either a hydrotreated (mineral modified) or a "synthetic" (such as a polyolefin or an ester) kind of fluid.

The wording "fully synthetic" may not be a "fully exact" definition after all.

Why not ask the opinion of the "big" makers who, no doubt, would be willing to answer queries of this sort.

Some synthetic greases are being marketed as synthetic. In fact they may be synthetic oil with non-synthetic thickener. Ask questions - get data sheets.

The new mobil oils have a lower ZDDP content than the API requires, with only small amounts of MoS2.

http://www.bobistheoilguy.com/moly1.html

Synthetic is the term used to describe the base oils which are used to make the final product, it does not include the additives.
There are many types of full synthetics but for engine oils ther are typically two. 1) is PAO ( poly alpha olephin) which is man made from small gas type molecules which are chemically combined to form larger oil molecules. This gives a very uniform fluid with predictable qualities, but at a cost.
The second type are hydrotreated oils. These are severely purified and chemically altered mineral base stocks or waxes. These too have a uniform structure and predictable behaviour but are not as "PURE" as the PAO. However are much more cost effective and for most of us, offer the high level of protection we want for our bits of gear but without hitting the hip pocket as hard.
Then there are the semi synthetics which combine mineral base oils with some amount of synthetic base oil to improve the performance. These are about third on this list in terms of oxidation stability etc.
I hope this helps!

Keep in mind that PAO lubricants don't mix well with other mineral or synthetic lubricants.  Makes a thick, gooey, varnishey stuff---yuck!

Rod

evelrod is mistaken and probably is referring to another base stock that is not around anymore for just that reason.  The name of it slips my mind and without referring to my file literature, I won't guess, but PAOs form the majority of synthetic base stocks out there and are full miscible with mineral oils.  It would be deadly for a company to market a non-miscible oil.  The lawsuits would be stacked up.

jimkden is right, evelrod may have thought of PIBs (polyisobutylenes) which also are polyolefins, but not PAO-type lubricants which are generally made from higher molecular mass straight chain alpha-olefins.

PIBs are commonly used in the adhesives and sealants industry. They are also used in the lube industry to prepare dispersant additives and VI improvers.

PIBs depolymerize and oxidize on heating, thus their use as base fluids is limited to metalworking and two-stroke lubricant formulations.

Okay, okay!  I "dropped and gave ya 20"!!! I really think it's the CRS syndrome that is creeping up on me.

Rod

Amsoil- the only true synthetic(according to Amsoil)?
Mobil 1 - made by Mobil,most common?
Shell- not available in 5W30
BP- not available over the counter
Valvoline,Quakerstate, Castrol - about the same price as Mobil 1.Claimed by experts(Amsoil) not to be made by the brand on the bottle.
Havoline and Walmart - the lowest cost.

Which one/s are the best value for money?
Why is Havoline synthetic so much cheaper?

Best value for the money - buy the one that warrants what they say for life expectancy and figure the cost per mile (or thousand miles).  There is only one that warrants what they say, it's not the cheapest to buy but is cheapest per mile.

I have had good results from Aerospace Lubes, Columbus, OH. Don't let the name scare you. They are very competitive, and they are a small custom operator serving many industries incl automotive.

Does Aerospace Lubes have API grades on the label, indicating the lubes have been subjected to and passed the API certification tests?

Contact Aerospace directly with your questions. Located in Columbus, OH.