Magnatec is not a true synthetic oil, and it says so right on the label (part synthetic). The MSDS says
3. Composition/information on ingredients
Ingredient name CAS # %
Base oil - highly refined Varies 85 - 90
Zinc alkyl dithiophosphate 68649-42-3 1 - 5
IDK where the remaining ingredients went, but the "cling" can be from anything. Oil or additive packs. I am not sure you can find engine oil on the market today that does NOT have additive packs. Anyway, the basic test is film strength as far as the product is concerned, because we care, in the end, about the results, not too much about how they are achieved. True synthetic BASE oils have naturally greater shear resistance and detergency than any BASE mineral oil, but you always want to protect the base oil because that is the last barrier between engine operation and engine destruction. So you use additives to give the oil "strength". If you look at two oils that test out equally in the lab based on physical performance (look up any of AMSOIL's tests), you don't know where that performance is really coming from.