Originally Posted by
HillRider
If this is a suspension fork, that oil does a lot more than keep things lubricated. It's volume and viscosity are critical to the damping function.
Damper oil is separate from the bath oil. And yes, the volume and viscosity matter a great deal to how the damping works. Fully agreed on that.
Everything is down to the specific fork in question, but on my Fox and RockShox forks the damper and bath oil are separate. The damper in my Fox fork is so complicated that I just hand it to a shop to service, but I change the bath oil at home. My older RockShox forks have more user-friendly dampers that I service myself.
And I'm behind the times. All my forks are years old.