[PhillipJ]

My second hand 2020 Fox 36 had some black gunk in the grease. Anything to worry about? Worth replacing seals next time I have the lowers off?


It doesn't suck down or lose pressure.

 

[Dougal]

Grease degrades and fills with rubber wear particles. Hence the black.

It's time for maintenance.

 

[PhillipJ]

Yeah it needed some attention, I don't think the previous owner even changed the bath oil.

I am surprised that so much can wear off the seal without the seal failing.

 

[wschruba]

Yeah it needed some attention, I don't think the previous owner even changed the bath oil.

I am surprised that so much can wear off the seal without the seal failing.

"Quad" rings have 4 (2 exposed) sealing surfaces. They can take quite a bit of abuse before they fail, compared to an o-ring. More friction, though.

Unless there are chunks of rubber (in the grease/missing), you're fine. New seals mean higher friction, so if it still seals reliably, use it.