I have found in general, rubber that is formulated or designed by Chinese companies is terrible. A very large reputable US manufacturer (like OEM or Dorman) will be good about making sure the correct rubber technology is in place even if made in china and I have had good experience using these.
You hit the nail on the head about rubber.
off topic ...
I replaced tie rod ends on my pickup in the fall , one was the lowest grade Napa part , the other a Duralast from Vatozone. The Napa boot split after a couple of months and yesterday I see the Duralast boot is all dry rotted ...
