What's Wrong with CRP/Conti or Elring or Meyle Valve Stem Seals
 

I'm really curious as to what all of the negative chat about "aftermarket" valve stem seals is for. I see the difference from the OE in the intake seal , but no difference in the exhaust seal.
Surely all of these good German companies can't be making bad valve stem seals that they claim "meet or exceed" OE manufacturers specs.
I ordered a set from a local MB dealers parts dept. and got Meistersatz /Conti- CRP , states on package "replaces 103 050 0058".
Any comments?

the times i've used them in rebuilt heads they have worked just fine. i think people replace their seals and expect them to work even though the reason their last set failed was because the guides were worn and the valves were wobbling. So they end up blaming the seal, and not the guide with over a 100k on them. just my opinion.....