So I'm looking to change my fork oil maybe on Tuesday.  In researching fork oils I found this awesome chart- http://www.mediaturbo.com/clients/marzocchi/forkoilviscosity.html

Clymers says to use 15wt fork oil.  For those who have changed either to 10wt or 20wt, what are the benefits you are experiencing?  What are the drawbacks?

diamond jim wrote on 06/21/09 at 07:47:04:


I've noticed much larger difference between old and fresh fluid than between 10W and 15W. I've used several viscosities and there's an initial difference but the viscosity goes off quite quickly. 20W might feel initially slightly harsh but after 30000 kms any fork oil I've used is like water, maybe not exactly but there's very little damping left. If the original 15W wasn't too harsh to begin with, you could try 20W because it might last just a bit longer before thinning out.

Amsoil advertises a synthetic fork oil that is supposed to keep its viscosity over time, and has antifoam agents to reduce shock fade when things get all bumpy and sloshy.  Sure it's over $10/quart, but any good stuff like Belray will run you almost that much anyway.

Another solution is to run 5W oil (so the viscosity pretty much has nothing to lose) and use cartridge emulators to dial up the compression damping to your liking.  I'm not sure if emulators are available for the Savage, but that's what I did on my dirt bike.. works great.