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Mineral Oil


FOB's picture

By FOB - Posted on 11 May 2012

Hi all,

Need to top up my brakes and am hunting down some mineral Oil, have found a few other branded ( Not Shiminao) Mineral oils cheaper . Can you top up with different mineral oils ? Or will I need to do a complete bleed and get out all the old oil which is Shimano ??

Cheers Sam

Brian's picture

I can't comment re brands but one thing I know is it is always better to buy small bottles and keep them sealed. Brake fluid is designed to be hygroscopic (absorbs water) so leaving them unsealed degrades them. Smaller containers have less air in them as you use it and also you tend to replace them more often.

browny's picture

TBH I would be running fresh fluid through there anyway whilst I had the chance.

AFAIK mineral oil isn't hygroscopic.

fastfreddie's picture

what brakes are you running,I have maguras and they use mineral oil.You can just top them up,but if they havent been bled for a while I would just do a clean change,one syringe full should do it.Freddie.

Discodan's picture

It doesn't have to be the same type or shimano oil at all, you can use Jack Oil which is quite cheap at an auto-one. In a pinch I've also topped up using 3 in 1 general oil without any issues. That's why I love Shimano rather than Avid which uses brake fluid which is fussy to look after and damaging to your paint etc

hawkeye's picture

... but mineral oil isn't, at least that's what I've read.

That's why I've bought a litre of the Shiman OEM stuff at $22.something from CRC.

That reminds me, I should probably use the bike free weekend it looks like I'm about to have (thanks, flu Sad ) to flush and replace the oil in both bikes.

Brian's picture

There you go. I was talking from a automotive background which its all dot fluid (if that's what its called). Personally though, in all my time mountain biking I've never had to bleed brakes so whats with that.

browny's picture

I did mine recently just because it seemed like the right thing to do.

The oil that came out was grey colour so at least it made me feel like I was doing something useful.

hawkeye's picture

@Brian, same here. I've never had them go spongy except once when I cut the hose to shorten it: got away without bleeding one, but not the other.

However, I've had issues with sticky pistons refusing to retract properly on one side of the caliper once or twice, and found that trail crap does get past the seals and contaminate the fluid with time. Looks like short bits of pale vegetable fibre. So I think a periodic replacement of the fluid is makes some sort of sense as a preventive measure, much the same as you do your car.

FOB's picture

Hi guys,

Cheers for the replys, it has been one of those days where I finally looked up from the spreadsheet that is slowly ripping out my soul and it's almost over so to answer any questions which may further help me.

Shimano Deore 535, back brake has started to be come very spongy over the last month, not sure why it's happened, have been going OTB a lot latley and finally realised last weekend that the rear has diminished significantly and I have been inadvertently using the front more, thus when I’m in a pinch and need to stop quickly.... and I though I was just out of practice

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