Mineral oil differences

thelonegroover

I appreciate the difference between mineral oil brake fluid, which is petroleum based and DOT 3, 4 or 5, which are synthetic. But are all mineral oil brake fluids the same. Shimano is about £20 per litre, while Castrol is less than £10 per litre. I know you don’t need that much but please bare in mind, I do live in Yorkshire!

nicklouse

well lets get this right.

DOT fluids 3/4/5.1 are glycol based and DOT5 is Silicon based.

mineral fluids are basically the same.

but can come in diferent "weights" viscosities.

LHM can be used in shimano brakes.

weeksy59

babyoil works just as well.

MAgura clutches are common on KTM motorbikes and use mineral oil.

It's not uncommon for people to use babyoil on them.

thelonegroover

Thanks, I'll check the price of baby oil. The other thing is. If baby oil and mineral oil brake fluid are so similar, why do they recommend warring rubber gloves when working with brake fluid?

weeksy59

Thelonegroover wrote:

Thanks, I'll check the price of baby oil. The other thing is. If baby oil and mineral oil brake fluid are so similar, why do they recommend warring rubber gloves when working with brake fluid?

They're not simillar, they're just hygroscopically similar and viscosity simillar, not a similar type of chemical makeup

nicklouse

Baby oil also has a lot of additives in it that dont want to be in your brakes for any length of time.

It is OK for a get me home but not for normal use.

RichMTB

DOT brake fluid is corrosive and will damage your skin after prolonged contact.

Minerall oil isn't corrosive but glove are always a good idea when you are working with the oilier bits of the bike.

konadawg

I used sewing machine oil which seems to be light enough and has been in my shimanos for years without issue. Cheap and you dont need to buy a gallon of it plus comes in a container with a handy nozzle.

mmacavity

LHM

Rolls-Royce cars use LHM, (just though that I would mention that.......... for no particular reason)

pdid

mmacavity wrote:

LHM

Rolls-Royce cars use LHM, (just though that I would mention that.......... for no particular reason)

So do Citroen, to take you to the other extreme.

Matt 24k

It's not just the viscosity of an oil that is the issue. Different types of oil are for different applications although they may be of the same viscosity. I would imagine that Shimano brake mineral oil has a chemical make up that allows it to deal with heat build up and not to damage the seals in the system. When Johnson & Johnson make baby oil I am pretty certain that they don't worry about it breaking down under heat but are more concerned about it not harming babies.
As for using baby oil in a motorcycle gearbox!

MarkLG

Matt 24k wrote:

As for using baby oil in a motorcycle gearbox!

He's not talking about putting it in gearbox. :roll:
The clutch is hydraulically actuated instead of a conventional cable - the method of operation is the same as a brake. I've used 5wt fork oil in a KTM clutch before without problems, and I imagine it would work just as well in Shimano brakes. I've also used LHM oil, but it's only usually available in litre bottles.
If you want proper mineral oil which is cheap then go to a motorbike shop and get a 100ml bottle of Silkolene, Plutoline or Motorex mineral oil for hydraulic clutches. Should cost around £4.