I asked Oberon's Director, Steve Street, about the seals in his slaves:
"Hi Nick,
We always have, and always will use slightly over spec EPDM Nitrile Rubber.
Our seals are actually machined from frozen material, they are NOT simple O rings like everybody else use. Our seals are purpose made 'U' seals with a carefully designed 'lip' that seals tighter the more pressure that is applied.
The black fluid is often a little misunderstood.
In addition to the cheap O ring that degrades. The original slave body/piston etc is NOT anodised as I am sure you are aware.
Just like when you clean a piece of alloy with polish and a clean cloth, the cloth becomes blackened from the alloy being polished off. The inside of the OEM slave suffers a similar effect. The Oberon Performance unit does not suffer this effect and so the fluid remains clear much longer.
NB; As the original master cylinder suffers the same issue - eventually blackening will still appear as the small piston in the master cylinder pumps back and forth creating the same issue - but over a much longer period of time.
You can confidently report that the Oberon Slave body and seals will practically last for ever... Unless massive use eventually wear's through the anodise (which I cannot imagine will ever happen) the fluid will never blacken unless it is being caused elsewhere, like the master cylinder as mentioned above. Or the slow mixing of any old fluid and residue from the past, remains within the brake lines etc...
To date, we still have 100% non failure of our seals.
After 17 years on the market, I reckon it is safe to say it is a proven remedy.
The wider audience will possibly be interested to hear your conversation. If you do post anything please send me a link.
Kind regards,
Steve Street
Director
Oberon Performance Ltd"
I must say I'm surprised he uses EPDM rubber rather than the more-expensive Viton, because Viton is way better at resisting solvents and has a greater heat tolerance. If I understand him right, the Oberon bore is anodised to resist the generation of black in the fluid from the aluminium being scuffed. Maybe Monster owners with black hydraulic fluid have been using the clutch too much?
