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Anyone tried Mineral Oil in a brake system recommended to use DOT Fluid???

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#4 ·
I. Hydraulic Brake Fluids:
Two types of fluids are typically used in braking systems; DOT Brake Fluid and Mineral Oil. The two groups have different base chemical compositions and properties and should not be mixed or substituted for in a brake system. Mixing or substituting these types of fluids will destroy rubber and plastic components within the system. It can also alter the performance characteristics of the brake system.

A. DOT Brake Fluids

DOT brake fluid is approved by the Department of Transportation for use in brake systems and is required to meet certain performance criteria, mostly consistent performance within a specified temperature range. DOT 3, 4 and 5.1 fluids are hygroscopic (water absorbing) glycol based fluids. These fluids absorb water at a rate of 2-3% per year. The result of this is a lower boiling point of the fluid because it is diluted with water. Brake fluid will not boil while under pressure. The automotive industry and all high end motorsports use DOT fluid for their braking systems. DOT 5 brake fluid is silicon based and should not be mixed with the glycol based fluids.

B. Mineral oil

Mineral oils are also used in brake systems but are not controlled by any specific standards. Mineral oil does not absorb water and can break down with time and heat. Low ambient temperatures will cause a mineral oil to congeal and the system to have sluggish performance (<20ºF). Some mineral oils are more environmentally friendly than DOT Brake Fluid, however oil is still an oil and should be disposed of properly.
 
#5 ·
While i haven't tried a full on fluid swap, I am using a Shimano hose, banjo, banjo orings, and banjo nut with Hope brakes and dot 5.1 . I had just build a frame up but the front hose was too short and really wanted to ride it the next morning so i used what I had on hand. Figured the orings would leak but at least i would have one ride on my new bike, been 5 years now with zero issues.
 
Discussion starter · #6 ·
suba said:
With all due respect someone with you're post count and rep power rating should already know the answer .....:)
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Ouch!!! ... ;)

Ratt said:
While i haven't tried a full on fluid swap, I am using a Shimano hose, banjo, banjo orings, and banjo nut with Hope brakes and dot 5.1 . I had just build a frame up but the front hose was too short and really wanted to ride it the next morning so i used what I had on hand. Figured the orings would leak but at least i would have one ride on my new bike, been 5 years now with zero issues.
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Thanks ... the seals in your caliper would have been 'made' to work with DOT fluid ... but good to know that the hose and whatever o-ring there was in the connectors stood up well ... :thumbsup:

I am looking at this from a logical point of view. Seals, to me are made of rubber (natural or synthetic) or something similar ... ie they need to be soft and flexible but at the same time keeping its shape. Oil to me is a substance that maintains the 'suppleness' of whatever so-called rubber or o-rings etc that i have and lubricates it at the sametime. I am no chemist graduate and hence do not have any fact to back this up. Alcohol on the other hand, to me, will destroy them as they do tend to dry them up, hence if something works for DOT fluids which is hygroscopic, then it will be fine with mineral oil ...

True ... manufacturers do have a warning not to use any other type of fluid, but is that something that they have tried and tested or more for conveniece and helping those consumers, who do not read the label and may have gotten the fluids mixed up? (You know ... some might not realise that the contents of a hot cup of coffee may be hot, and needs to be reminded as such)

Apologies if some of you may feel frustrated and feels that I should just follow recommendations by manufacturers, as they know what they are talking about and me as a consumer do not ...
 
#7 ·
Since seal kits were easily available for Hope i would have tried this myself but.. I was on older mono minis with the metal (non-phenolic) pistons and was cooking the fluid to where floaties would form and clog the reservoir hole, i had to switch to dot 5.1 from 4 to get away from the problem. The lower boil point of mineral oil worried me.

Although dot is problematic on paint and can be corrosive on metals I've had mineral oil do weird things to plastics and rubber grips too.

chinaman said:
....True ... manufacturers do have a warning not to use any other type of fluid, but is that something that they have tried and tested or more for conveniece and helping those consumers, who do not read the label and may have gotten the fluids mixed up? (You know ... some might not realise that the contents of a hot cup of coffee may be hot, and needs to be reminded as such)

Apologies if some of you may feel frustrated and feels that I should just follow recommendations by manufacturers, as they know what they are talking about and me as a consumer do not ...
Click to expand...
phfft, been doing ghetto tubeless for 10 years, heard those warnings before.
 
#8 ·
chinaman said:
Just curious ... :skep:

Will the mineral oil damage the seals etc?
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Depends....

If the elastomers have been exposed to the DOT fluid they will have absorbed some.....then when exposed to the mineral the elastomers will have to de-sorb the COT fluid to some degree and then absorb some meneral oil....This direction is not too bad really. but the elastomers will swell somewhat.

On the other hand if the seals have not been exposed to DOT fluid..then the mineral oil is very unlikely to casue any problems what so ever.

If one goes from mineral oil to DOT fluid well that tends to be the worst case, the elastomers will likely swell far too much to provide good preformance...DOT Fluid is more agressive than nimeral oil...

Also even if the mineral oil elastomers are dry and then exposed to DOT fluids..problems are likely.

Oh yeah and mineral oil works just fine to -35 C.
 
#9 ·
Hi,

Sorry to revive an old thread, but if it helps anyone... I had a pair Clarks S2 brakes which needed hose cutting and bleeding, but not knowing they were DOT4 brakes i used mineral oil from Shimano and screwed up the rubber seal on the lever reservoir.

Curious enough i had a pair of LX Dual control Disc Brake levers about and connect them to the Clarks callipers, filled with Mineral oil, proper for Shimano levers and good to go for about 2 years now... great performance, better than the original Clarks levers, and no oil leaks.

Glad if it helps anyone.
 
#10 ·
dramatic swelling of mineral-seals in DOT 4 fluid

Same conclusion but you may interested in seeing dramatic swelling of mineral-oil seal in contact with DOT 4 brake fluid at www . largiader . com / articles / mineral (sorry, I am not allowed to post real URLS)
 
#13 ·
i know this is a old thread but i was wondering the same thing, i have shimano XT brakes and it calls for that mineral oil that i would have to order. one of the local mechanics uses 2.5 wt fork oil on his brakes and his brakes feel absolutely amazing, and he has had no problems for 3 years.

so i guess my question is... can i use DOT 5 ? or just order mineral oil?
 
#14 ·
I would buy the Shimano oil. There are other brands of brake oil that are cheaper ie Magura Royal Blood Mineral Oil there are other brands too Juice Lubes Mineral Oil Brake Fluid . no idea if they are suitable for Shimano brakes. Do your own research.

I would NOT use DOT fluid or "baby/mineral oil" from the drug store. There are threads on using mineral oil for auto brakes.search, Again not for me.
 
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#19 ·
subarumtbjrk said:
i know this is a old thread but i was wondering the same thing, i have shimano XT brakes and it calls for that mineral oil that i would have to order. one of the local mechanics uses 2.5 wt fork oil on his brakes and his brakes feel absolutely amazing, and he has had no problems for 3 years.

so i guess my question is... can i use DOT 5 ? or just order mineral oil?
Click to expand...
Shimano Mineral Oil?
 
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