Orangutanracer's question about the different o-rings is definitely interesting. Friction is always a topic of discussion at every level, and deserves a test. Friction tests, to do them properly, require a bit different methods. I did a quick and dirty by just running a shock with no oil at the same speed I ran with oil and got a result. The result show I had about +/-1N of force. Comparing that to the 10-20N that the damper provides it's not much, but many would argue it is still significant. I did get a different brand shock from a friend, and I did notice and measure a larger amount of friction from the seals. So, as the quote above says, I'll try to design a test that shows the significance of the sliding friction vs the overall performance. If it proves significant enough, then maybe a specific seal type test is in order.

Thanks for the feedback.