Results 1 to 18 of 18
  1. #1
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650

    Alternate Fork Oil - Suggestions?

    NEW EDIT I was a bit presumptuous in my initial post by thinking nobody else would feel like responding to my question. Sorry about that. If you have some input, by all means post it up. I'm always interested in alternate ways of doing things that can result in better performance and/or lower maintenance costs./NEW EDIT

    I'm planning my winter indoor activities and on my list is an overhaul of two additional SID forks. On my previous overhauls I've used the Finish Line fork oils. Since I'm running low on my existing oil supplies, I'd like to try some of the alternatives previously mentioned in the forum.

    Here's what I gathered:

    * Use 80w or heavier synthetic gear oil in the air chamber
    I plan to use Valvoline 80W-90 Durablend synthetic gear oil.

    * Use Mobil1 5w-20 synthetic engine oil for the bath oil in both legs (15ml).

    * 5wt to 7.5wt suspension oil in the damper
    I was using Finish Line 5wt (reportedly 22 cst @40c) and I wouldn't mind moving down a bit to something thinner. I can get Bel-Ray 5wt fork oil (reportedly 17.1 cst @40c) locally and will probably try it out.

    Also, I'll be replacing the seals with Enduro fork seals. I've seen recommendations for packing grease in place of the factory foam ring. Would it be recommended to pack grease between the oil seal and the wiper when using Enduro seals? Or, should I just leave that area dry?

    Thanks in advance for all of your help!
    Last edited by marpilli; 11-01-2012 at 05:58 AM.
    Contact information: http://about.me/marpilli

  2. #2
    Save Jesus
    Reputation: beanbag's Avatar
    Join Date
    Nov 2005
    Posts
    2,694
    I'm not bad mechanic, but I will attempt to answer some of your questions anyway

    Air chamber: I have found it doesn't really matter what oil you run here. Rock Shox recommends you run the bath oil. The gear oil I have found to be a sticky gooey mess. But I wouldn't be surprised if it worked. My guess it that it will have more dynamic drag.

    Bath oil: Everybody likes to run syn motor oil. (although usually 5-40) RS recommends a heavier fork oil. I run way oil. It has better cling properties than motor oil. My brother claims the way oil has more dynamic drag. I think it is fine. If you have problems getting the last few mm of travel from your fork, you can reduce the amount of bath oil on the damper side.

    Damper oil: Running a lower viscosity oil will only reduce damping due to shims. Otherwise I doubt the brand of oil makes a big difference. PMK has warned that you don't want to use a high VI shock oil because it is not designed for running exposed to air.

    I don't recommend anything more than a thin coat of grease between the dust wiper and oil seals for assembly purposes. If you pack it in, it will just come out onto the stanchions after a ride and make a mess. The purpose of the oil seals and stanchion surface finish is to actually leave a microscopically thin layer of oil on the stanchions. This is your lubrication.

  3. #3
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650
    Thank you for the input. Maybe a little more drag in the air chamber will be offset by a little less drag in the damper?

    I believe the specified oil for the damper is the RS 5wt (about 15 cst @ 40c if I remember correctly) and I've been using a slightly higher viscosity Finish Line 5wt (22 cst @ 40c). Will I really notice a difference if I kept all things the same and switched to something in the 15-17 cst range?

    My ultimate goal is to use locally available products (hopefully at a cheaper price) if it will be a decent substitute. I don't really want to go about buying any more of the "bicycle fork oil" if I can help it.
    Contact information: http://about.me/marpilli

  4. #4
    Save Jesus
    Reputation: beanbag's Avatar
    Join Date
    Nov 2005
    Posts
    2,694
    The answer to your question depends on what rebound and compression damper you have. If you have the older style port orifice only rebound damper, then the viscosity of the oil won't make that much of a difference because orifice flow is primarily dependent on fluid density, not viscosity. If it has some shims, then you will have a little less high speed damping, or a more digressive damping curve.

    Same with the compression damper. If it is the older style motion control, then it is orifice flow and blowoff only, so again the viscosity won't matter that much.

    The rebound damper in Rock shox forks in general does not have that much friction by itself as it is not load bearing, so that's why the quality or lubricity of the oil is not critical. As long as it is good at anti-foaming.

  5. #5
    PMK
    PMK is offline
    mtbr member
    Reputation: PMK's Avatar
    Join Date
    Oct 2004
    Posts
    2,243
    What exact fluids are available locally to choose from?

    Nothing you have mentioned would be a first choice in items I work on.

    PK
    Reps! We don't need no stickin' reps!

  6. #6
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650
    PMK, I doubt that I can inventory the local automotive and motorcycle parts stores to put together that list for you.

    Would you suggest any particular brand/product normally used for automotive or motorcycle maintenance? If so, I'll take it into consideration and call around to check availability.
    Contact information: http://about.me/marpilli

  7. #7
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650
    beanbag, the SIDs in question are both 2001-2003 era (one SL and one WC).
    Last edited by marpilli; 11-01-2012 at 06:48 AM.
    Contact information: http://about.me/marpilli

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    5,836
    Quote Originally Posted by beanbag View Post
    I'm not bad mechanic, but I will attempt to answer some of your questions anyway

    Air chamber: I have found it doesn't really matter what oil you run here. Rock Shox recommends you run the bath oil. The gear oil I have found to be a sticky gooey mess. But I wouldn't be surprised if it worked. My guess it that it will have more dynamic drag.

    Bath oil: Everybody likes to run syn motor oil. (although usually 5-40) RS recommends a heavier fork oil. I run way oil. It has better cling properties than motor oil. My brother claims the way oil has more dynamic drag. I think it is fine. If you have problems getting the last few mm of travel from your fork, you can reduce the amount of bath oil on the damper side.

    Damper oil: Running a lower viscosity oil will only reduce damping due to shims. Otherwise I doubt the brand of oil makes a big difference. PMK has warned that you don't want to use a high VI shock oil because it is not designed for running exposed to air.

    I don't recommend anything more than a thin coat of grease between the dust wiper and oil seals for assembly purposes. If you pack it in, it will just come out onto the stanchions after a ride and make a mess. The purpose of the oil seals and stanchion surface finish is to actually leave a microscopically thin layer of oil on the stanchions. This is your lubrication.
    "way oil" - what is that?

  9. #9
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650
    If it wasn't a typo, then he's referring to a machinist oil used for milling/lathing.
    Contact information: http://about.me/marpilli

  10. #10
    Save Jesus
    Reputation: beanbag's Avatar
    Join Date
    Nov 2005
    Posts
    2,694
    Mobile Vacuoline 1409 or Vactra #2, for example. Bum some off of a local machine shop but don't try to buy it yourself.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    7,693
    Quote Originally Posted by marpilli View Post
    * Use 80w or heavier synthetic gear oil in the air chamber
    I plan to use Valvoline 80W-90 Durablend synthetic gear oil.
    That should work fine. You just want a good, heavy oil in there. The heavier oil isn't going to cause an increase in drag.

    Quote Originally Posted by marpilli View Post
    * Use Mobil1 5w-20 synthetic engine oil for the bath oil in both legs (15ml).
    That's what I use. I like it because it works well and is easy to find anywhere.

    I remembered Beanbag talking about using way oil before (see link below) and I tried to get some myself to try, but I was never able to find it for a reasonable enough price and eventually gave up. Beanbag, any chance you'd want to sell me some cheap?

    Quote Originally Posted by marpilli View Post
    * 5wt to 7.5wt suspension oil in the damper
    I was using Finish Line 5wt (reportedly 22 cst @40c) and I wouldn't mind moving down a bit to something thinner. I can get Bel-Ray 5wt fork oil (reportedly 17.1 cst @40c) locally and will probably try it out.
    I've used Bel-Ray before and it was fine. Since it's only handling the damping you don't need to worry about its lubricating properties too much.

    Finish Line oil is rubbish.

    Quote Originally Posted by marpilli View Post
    Also, I'll be replacing the seals with Enduro fork seals. I've seen recommendations for packing grease in place of the factory foam ring. Would it be recommended to pack grease between the oil seal and the wiper when using Enduro seals? Or, should I just leave that area dry?
    I just put a big glob on grease in the wiper, mushed it around well, and leave the extra.

    You might also find this thread useful:
    Better clinging oil than Fox's red and green oil ?

  12. #12
    mtbr member
    Reputation: marpilli's Avatar
    Join Date
    Feb 2011
    Posts
    4,650
    Thank you for the response. Regarding the Finish Line usage, forgive me as I was young and dumb. Well, I'm not much smarter now...

    I've called around to a few motorcycle shops in the area and they all carry heavier weight oils in-stock. They have all told me they can only order the lighter weight (what I need) by the case. And, they understandably hesitate to order a case if I'm only buying a quart.

    I plan on printing out the PVD viscosity wiki and just paying a visit to the closest shop to see what they have and what they can order that's close to the RS recommended rating. Are there any particular brands I should avoid (like Finish Line)?
    Contact information: http://about.me/marpilli

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    7,693
    If you just use the chart you should be able to find something in stock pretty easily.

    Avoid Silkolene.

  14. #14
    mtbr member
    Reputation: shapirus's Avatar
    Join Date
    Jun 2009
    Posts
    488
    Quote Originally Posted by bad mechanic View Post
    Avoid Silkolene.
    Why? I am using Silkolene Pro RSF 2.5w in my Revelation and so far it's been excellent in every regard, except for winter use which I haven't had a chance to test yet (I actually decided to try it due to its high viscosity index which should prevent it from getting too viscous in low temps).

  15. #15
    Save Jesus
    Reputation: beanbag's Avatar
    Join Date
    Nov 2005
    Posts
    2,694
    search for threads on why PMK doesn't like the silkolene pro RSF
    Last edited by beanbag; 11-02-2012 at 03:22 PM.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    7,693
    Quote Originally Posted by beanbag View Post
    search for threads on why PMK doesn't like the silkolene pro RSF
    And PMK isn't the only one who's had issues with Silkolene.

  17. #17
    moaaar shimz
    Reputation: tacubaya's Avatar
    Join Date
    Jan 2006
    Posts
    8,956
    Yep, avoid Silkolene. It should only be used on rear shocks and close cartridges like Fox FIT or Marzocchi TST.

    Way oil works well as lower lube, specially if there is very little lubrication or there is existent stanchion/bushing damage.

  18. #18
    mtbr member
    Reputation:
    Join Date
    Feb 2010
    Posts
    1,426
    Because of the differences between oils W of the same weight from different manufacturers, the key is just to find a brand that is readily available to you and stick with that. Instead of buying another brand 5W, get a bottle of 2.5W and 5W and use it to experiment with lighter options. I'd immediately go the 2.5W to compare/contrast, then mix up some sort of 2.5-5W blend to dial things in just how you like it.

    For air piston lube, I now just use silicon grease in my 2001 SID, 2009 SID and 2007 Reba. It doesn't migrate down below the piston and keeps things stiction free between services (which I do every 50 hours max).

    For the lowers / splash lube - Mobil 1 0-40W (its what I have in 20L drums for my cars) - but any good synthetic motor oil will do.

    The recommended weight oil on the 2001 SID is 15W. I am running mine with 5W Mobil fork oil on my daughter's bike because the positive air pressure is only 35-40psi for her weight. Even so the rebound damping is very fast. If you need 2.5W oil there may be something wrong with the rebound damping circuit. The 1/4 turn rebound adjuster on these forks is not a great design, perhaps there is some obstruction there?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •