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Oil for magura HS33


La Bourde
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Hi,

 

 

I recently bought a(n used) pure competition trial bike. It has a new HS33s with the original Magura Blood fluid.

Many many years ago, I owned already one (Koxx code) with HS33. Later I bought a comp stock with disc (Avid juicy in 200mm, about 15 years ago!) 

I was never a big fan of HS33. And having - good - experience with discs, I don't really understand why pure competition bike still use HS33. It might be lighter, less exposed and have less play but with disc you can nicely modulate your braking and they are now powerful enough (with the right brake pads). But I digress.

I struggle to get used to this on/off behavior of the brakes. I had mechanical and hydraulic discs on my street/trial (I have also a frame with Vee) and I am used to the progressivity of the bike, I let roll the bike a lot. 
I supposed too, that the lever does not come back fast enough, which amplify the on/off issue. I recall that many riders used water to bleed their magies. Recently I saw Jitsie and other brands sell a special oil (but they surely get it from somewhere).  So I decided to bleed the front brake with Shimano disc oil, that has a really low °CST. It feels much better now.

Today I ordered Putoline HPX 2.5R oil and I think I will bleed the rear brake with. I read indeed that it has one of the lowest °CST on the market, even better than the Shimano oil. This oil is used by some German guys to fix the moving bite point of the Shimano disc brakes. I will let you know how it feels once done. It could be a nice alternative, cause it is cheaper that the Jitsie or Trialtech brake fluid.

  • Do you have some experience with this kind of fluids?
  • Do you know the CST values of the Jitsie fluid or Trialtech?
  • Did you ever encountered leakage due to usage of a low viscosity fluid?
  • For those that were used to disc brakes and now ride HS33, did you have to adapt to them? I mean I had not problem with Vees (the rims were not grinded though)

 

 

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It’s worth double checking if that oil is compatible with magura before you ruin your brakes. I know for sure that .5 oil (used on hope disc brakes) doesn’t work on magura, so “2.5” alone sounds risky to me let alone the brand.

As far as I know the trialtech fluid is a mixture of antifreeze and distilled water and at one point I must have been interested in making my own fluid as I’ve saved this diagram on my phone:

 

593A0ECF-51BF-4C2A-9668-937410453E57.jpeg

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Thank for your answer.

It is a synthetic oil, used in fork suspension. 2.5 means here the "viscosity" of the oil, it is its SAE value (SAE=Society of Automotive Engineers). The lower the value, the less viscosity. But this value is not really a reliable metric, it is better to know the cSt (kinematic viscosity in centistokes) at 40° for example, which is really low for this oil (can't find the chart I saw).

So it is not a DOT based oil. As I wrote, some people use it also to fill Shimano brakes, which use mineral oil, so  I will be fine.

 

 

Edited by La Bourde
Synthetic oil, not mineral
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I am not familiar with that brand, but I have used 2.5 wt shock oil from Finish Line for years in my brakes and have found it to be dependable and not cause any problems. I don't know how it compares to the Jitsie or other performance trials fluids, but it seems a little bit more responsive than the stock Magura blood.

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I've been using the Putoline HPX in my Magura disc brakes for a few years. All good, no leaks or swollen seals, even though it's a synthetic oil. It's definitely thinner than Magura oil, but on a disc brake can't say I noticed a difference in feel. I've also used Citroën LHM+ oil, but I find it's a bit on the thick side.

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Thanks, that sounds great. You are right, the Putoline HPX is a synthetic oil, not a mineral oil as I wrote before. I used LHM+ years ago and I can confirm your feel. It was thicker than the Shimano disc oil for example. I think the difference of viscosity is easier to notice with HS33. The system uses a lower pressure than disc brakes (the master piston diameter is 14mm on HS33 compared to 9mm on some Shimano disc brakes, so the surface difference is huge, more than twice)

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So I have bled my rear HS33 with the Putoline oil. The front brake uses Shimano mineral oil. Compared to the original oil, the Shimano one is already much thinner, one can really notice the difference, the lever comes back much faster. With the Putoline, this even more the case, but the difference is less between Putoline and Shimano than Shimano and the original oil. The lever is really easy to activate, there is almost no resistance. First ride this week hopefully.

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Hi,

 

so I eventually rode on Sunday, the weather being better that forecasted.

Bleeding with the Putoline was not a problem at all. It is almost transparent.

 

I am not sure if it is related to the change of brake fluid, but I had a very nice session on that day.

I had the impression to have a better control on the rear wheel. Previously the brake pads came back really slowly.

The rear brake felt much better than with the original Magura oil filled in: it seems that I required less force to actuate the lever, which is a nice improvement too.

Overall, I really appreciated the change and did not find any drawback. 

 

There is a small improvement compared to the Shimano oil (the front lever still uses Shimano mineral oil). The viscosity of the Putoline HPX is definitively less than the Shimano one: the lever required less force and it come back faster.

 

Unfortunately I never run water (that damages brakes) or Jistsie/Trialtech brake fluid, so I can't compare with.

 

My recommandations:

  • if you already own Shimano oil, use it.
  • if you want something better: Putoline HPX 2,5 (or maybe Jitsie/Trialtech brake fluid)
  • if you don't own Shimano mineral oil, go for the Putoline if its price is OK (I paid the same as for Shimano oil) 
  • the viscosity of the original Magura oil or LHM+ is higher, so prefer either Shimano or Putoline 

 

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