Dragboat, You have some interesting points to the seals composistion and here is my thoughts on how the 131 handles this as opposed to the motor oils.
The 131 is designed to be used in transmissions, hydraulic systems, motor oils, gear boxes and fuel systems. All of these would varying different types of seals. Interesting enough, each have their own elastistic properties and each affected by lubrication.
Now if the 131 for example had alcohol in it (which it doesn't) that would tend to dry out a seal of any nature, this is most common in fuel system treatments and does cause seals to dry and crack.
Another interesting little test I've done was to put the 131 in a white disposable coffee cup ,something that pb blaster would cut right through in just minutes, and let it sit for a week and it never even made a dent in it No leaks, no nothing. This tells me it is not a harsh chemical on that coffee cup, then it would not cause me problems with seals.
Not being the chemist, I rely on the experience that this company has and have found so far, they have been nothing less than supurb in making products that hold up to their claims.
So if a motor oil has these so called seal conditioners, I would have expected to see some kind of reaction to these seals as the valve stem seals are of a material used in motors, and as for the O rings, they too are used in the automotive industry, so there's a good chance it would have had simular reactions as I demonstrated in the measurments. Both the valve stem and the O ring seals had conditioned at about the same, .25mm with the neutra 131 whereas no motor oil did anything like that to either of them.
So in a nutshell, I don't believe that any of the full synth's have any amount of seal conditional ability. What they do have is the ability to maintain an already conditioned seal/engine, proven by the fact it was able to disperse more crude off the used valve stem seals in this case.
