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Marzocchi Oil

staike

Monkey
May 19, 2011
247
0
Norway
I bought some Silkolene Pro RSF 7,5 WT to replace the oil in my 2007 66 RC2x. Looking on the cSt values for the oils it appears like the stock oil is 26.1 cSt and the Silkolene is 37.19 cSt. I understand that this will affect the suspension, but how much? Will it be totally crap? I read that older Marzocchis works better with thicker oil than stock, can anyone confirm this? I'm selling the fork, but I want to change oil on it first as it haven't been done in a couple of years (still works goood though!). Viscosity Index is 150 for the stock oil and 322 for the Silkolene, I guess that's good??

What about using the same oil in a Fox DHX 4.0 2010? I tried to find some numbers on the stock oil used, but couldn't find it.
 

go-ride.com

Monkey
Oct 23, 2001
548
6
Salt Lake City, UT
Two things:
1. Yes the higher CST oil will affect the feel of the fork on small bumps or high speed chatter.
2. The last time I used Silkolene oil in a Marzocchi the fork did not like it. It felt very sticky. I think the seal swellers in the Silkolene negatively affect the Marzocchi bushings.
 

staike

Monkey
May 19, 2011
247
0
Norway
Thanks, so what you're saying is that I shouldn't use the oil at all? I have used the same oil on my brothers 66 RV 2007 and it feels fine, maybe a little sticky, but not noticeable at speed.
 

go-ride.com

Monkey
Oct 23, 2001
548
6
Salt Lake City, UT
I like Torco a lot better and have had good luck with Maxima. We used to use Silkolene, but had stiction issues. Something that probably wouldn't be noticed on a heavy Motocross bike, but was obvious on a Mountain Bike.
 

baca262

Monkey
Aug 16, 2011
392
0
Thanks, so what you're saying is that I shouldn't use the oil at all? I have used the same oil on my brothers 66 RV 2007 and it feels fine, maybe a little sticky, but not noticeable at speed.
i've also heard something about silkolene and marz not liking each other on my local mtb forum so try to get something else.
 

Huck Banzai

Turbo Monkey
May 8, 2005
2,523
23
Transitory
Many moto fork oils have seal conditioners in them that are designed to cause seal swelling; as Krispy points out this isn't something you notice on a heavier MX fork, but very much so on an MTB fork.

It can also impact the longevity of the seals that weren't designed with those conditioners in mind. (swollen/binding ultimately is wear inducing to some extent.)

I have gotten this shpiel from MZ, and they have always recommended Golden Spectro oils for their forks. (I have 1l of 125/150 and 1l of 85/150 each right here)
 
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Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Agree with go-ride, I just posted about the same thing recently here.

In fairness to the product, it's a high-VI shock fluid (the S in RSF), so it probably wasn't really intended to be used in open bath / lower lubrication applications anyway.

It works brilliantly in sealed dampers, but I would use something else in your application. Both Spectro and Motul worked very well in Marzocchi when I rode them.