Re mixing fork oil weights.

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  • Re mixing fork oil weights.

    An oil thread!

    Do we have an oil expert in the house.
    What do I get if I mix equal volumes of same brand fork oils.
    The mix is 10w and 5w.
    My maths says 7.5w. However I suspect its not that simple.

  • #2
    You would be right on the money. The hard part comes into play when you don't like the 7.5 and you want to start thickening or lightening up even more!
    """""""Darksider #10 It's been said by many people, that I am still only 16 years old inside my head!! LOL!!
    I have never thrown a leg over any make or model of motorcycle and had nothing but a good time!!"""""""

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    • #3
      I use 10w and never look back.

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      • #4
        I used to do that kind of thing back in my dirt bike days. I finally came to the realization that if I just bought the right oil in the first place, everything worked fine and I quit making a mess of the shop floor.

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        • #5
          Originally posted by billybob View Post
          I use 10w and never look back.
          Its not going in my Wing. Its for a Triumph scrambler. There is 10w in there at the moment, and I wish to have it a little softer up front.
          I don't have bucket loads of $ to throw at it to improve it and thought I would start with the oil.

          So Rick. Ha ha onyamate. Re right on the money. I would end up with 7.5W or its not that simple?? :confused:

          I have already 10w and 5w, if I can mix my own why buy more??
          GL1800 8A - TRIUMPH SCRAMBLER 900

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          • #6
            If it was me, I'd go straight to the 5W and see how that feels. I'm not sure a drop of 2.5W will be that noticeable. Let us know how it works out for you.

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            • #7
              Since the last response was over a week old I wasn't going to respond to this thread but decided to just for future reference.

              Kiwi as it has been a week since you posted, I'm guessing that you have already changed fork oil and hope you just went with Jim's suggestion to use the 5w.

              Suspension fluids often have a viscosity weight rating rating on them simply because the general public expects oil to have these numbers. When working with lighter weight oils the viscosity index is what really matters and how fluids should be compared for viscosity. If you look at the chart on this link

              you'll see that not all manufacturers even use the same weight rating for the same viscosity fluids. RockShox 2.5 and Torco RFF 5 have the same viscosity numbers, so to be consistent in making changes you should always stick with the same manufacturer. As far as mixing suspension fluids to arrive at an in between viscosity, you can but it must be done based on the viscosity index. AND NEVER mix fluids from different manufacturers, very often the additives do not play well together and there is no telling what you will end up with.

              There's a lot of information on this on the web, and my knowledge from working with this stuff in the mid 70's is going away. Faster as the days go by.

              Clear as mud?

              Black 2008 Goldwing Level 4
              Northern Kentucky

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              • #8
                I have not done the job yet.
                I have bought a bottle of 7.5. as I did not have enough 5W to do both forks.
                I also have constructed a device with a large syringe to make smaller adjustments to the level.

                Ahem. That information is very informative.
                I must confess I was getting confused until I found this

                I hear your comments with the mixing of oils and brands.

                I hope to get it done today, along with a few other jobs on the Triumph.
                GL1800 8A - TRIUMPH SCRAMBLER 900

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                • #9
                  I finally made it out to my shed.

                  I changed out the oil from 10w @ 123mm to 7.5W @ 140mm from the top.
                  While I'm not much of a Burt Munro I do like to try some things and see how it works out.

                  I went for my usual ride to where I work in a break between the showers here today.
                  There are a couple of corners where I really had to hang onto the bars due to the bumps.

                  Result was it glides over the bumps with hardly a movement. Success.
                  And that bloke Murphy showed up 1/2 way through and I came back considerably wetter than when I left.

                  Thank you for replying to my pondering.
                  GL1800 8A - TRIUMPH SCRAMBLER 900

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                  • #10
                    I'm glad it worked for you!

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                    • #11
                      Wet but smiling, that's the ticket. Glad you found the sweet spot.

                      Black 2008 Goldwing Level 4
                      Northern Kentucky

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