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Despite the universal disapproval of my suggestion I fail to see how taking two oils made by the same manufacturer for an identical purpose that differ only in viscosity and mixing them in equal measure could do other than cause the resultant mixed oil to have a viscosity somewhere between the two original oils. We're talking fork oil folks - not high detergent stuff for turbocharged engines revving to over 10,000 rpm - all it's got to do is stop them sticking while being forced back and forwards through little holes...

DanielMc wrote:Despite the universal disapproval of my suggestion I fail to see how taking two oils made by the same manufacturer for an identical purpose that differ only in viscosity and mixing them in equal measure could do other than cause the resultant mixed oil to have a viscosity somewhere between the two original oils. We're talking fork oil folks - not high detergent stuff for turbocharged engines revving to over 10,000 rpm - all it's got to do is stop them sticking while being forced back and forwards through little holes...

I'm with you Daniel.
I have to be 'cause that is what is in my forks - home made BelRay 7.5

DanielMc -

It's more than just viscosity...oils, and I think fork oils would be the same, all start from a base stock...I'm simplifying things here a bit. Then the base stock is "manipulated" to achieve each of the various offerings. Those additives do more than create the viscosity rating on the side of the bottle. So, being your own mixing agent, you are combining things in a way not meant to be combined. And it's possible that the original mixing to create say 5wt and 10wt is not done by simply just pouring things together on a bench...maybe temperature or humidity or whatever is required...so that pouring them together at room temperature doesn't do squat. I don't think we would have any idea of what we had...an it might even be detrimental.

But give it a shot. IMO, I don't see how your average rider can really notice this difference...maybe trying 5wt and then trying 10wt...but it would seem there are other variables at play that we can't control or don't know that are having an effect and we come up with a wrong conconslusion about what we've done.

My 0.02...Kurt in S.A.

I just sent the question in an e-mail to Belray.
Stay tuned.

http://widman.biz/English/Calculators/Mixtures.html


Some interesting stuff.

ME 109 wrote:Any good brand I think, 7.5 wt. for average joe.

I've tried quite a few different weights, and have settled on 7.5 with the BMW HD springs for my R100S.

I've usually done the 50:50 mixture thing too, aiming for 7.5w and find it interesting, that using the tables robtg provided suggest the result is less than expected. It's not a huge difference, but a difference nonetheless.

I wish I could find that article on suspension fluids, as it seems that although a few people sell 7.5 very few actually have one - it is usually either 5 or 10 with a different label.

And the viscosity of 5 or 10 varies from brand to brand too

Except for the top shelf Synth HVI suspension fluids, and they dont compare well with dino oils anyway, as they are inherently multigrade.

So mixing dino yourself to get 7.5 is probably the best way to go, if you cant afford the good stuff.

And you know who's oils are true to grade.

I thinkthat we are getting too hung up on labels, I found that 5w was too soft and 10w too hard, mixing the 2 50/50, seems to be fine.

As an aside racetech, the makers of cartridge fork emulators, say on their web site that the 'weights' of fork oils seem to vary very widely between fork oil manufacturers, so their advice is to choose a manufacturer and to stick with their range of oils , finding a nominal viscosity that works for you

dougie wrote:I just sent the question in an e-mail to Belray.
Stay tuned.

Good idea Dougie - be interested to hear what they have to say.