Hydraulic oil as a replacment for clutch brake fluid.

[circlework]

Hi All,

Reading clutch master cylinder threads on here has made me wonder why a light hydraulic oil such as Castrol Hyspin AWS32 isn't used in place of brake fluid. Sure would save some grief with paint removal etc' when the seals eventually give up and to that end, hands up those that haven't spilt some on a refill, or am I the only five thumbed critter in the room?

Be interested in your comments and to find out if anyone is actually using it.


Cheers,
Daryl.

[Brid]

Hi Circlework

While hydraulic oil would be fine from the point of corrosion control, lubricity, etc, the thermal expansion would cause issues. Brake fluid doesn't expand to any significance with rising temperature, whereas hydraulic oil will.

The consequences would be that as fluid heats up, you'll notice the free play in the brake & clutch pedals diminish. In fact, the brakes will start to drag as the fluid between master cylinder calipers/wheel cylinders expands...not good!

Regards
Brid

[richard4u2]

i was told once that it will swell the cups in the cyclinders

[Dougal]

Heat isn't usually a problem on clutch cylinders. Silicone based fluids are available as a straight replacement if you want to get away from DOT types.

It does sound like a solution looking for a problem though. If you've got fluid leaking or needing topped up then the problem is the leak, not the fluid type.

[Tank]

I used to run Hydraulic oil in the power steering of my trucks and it cured the many leaks I had when using ATF, why not contact an oil company website or Rick-130 and get professional advice, Regards Frank.

[bob h]

i was told once that it will swell the cups in the cyclinders

Sure will, tried some once as an emergency stopgap. Had to renew all the rubber cups and seals in the m/cyl. Bob

[JDNSW]

Conventional seals (and probably hoses) will be chemically attacked by hydraulic oils and will fail quite rapidly.

A good example of the problem is given by Citroens. Up until 1967 the very elaborate hydraulic system on Citroen cars used a special fluid (LHS2) that was effectively the same as heavy duty brake fluid. It was then replaced on new vehicles by a mineral based fluid, (LHM) that is very similar to an automatic transmission fluid. As a result, every rubber component in the system is different - look the same, but different, causing serious problems if the wrong part or the wrong fluid is used. (They tried to minimise this by a change in fluid colour from red to green, with matching changes for parts packaging, and painted bits changes from black to green.)

John

[circlework]

I was only talking about the clutch due to the high temps in the brake circuit.

OK, well that surely answers my question...... obviously the seals that are resistant to degradation by brake fluid, aren't to hydraulic oil.

And speaking of using hydraulic oil in the power steering, Ive been doing that for decades ..... Hyspin AWS46. But, I'm not recommending it, coz I'm no expert.

Thanks for your replies.


Daryl.

[Blknight.aus]

engine oil works fine, the rubber in the seals is the same as the rubber in the engine seals (usually)

but when its cold if you go too heavy you can get a very slow clutch return and it may even wind up dragging.

a monograde 10 or 15wt engine oil would probabley be your best hope if you want to go that way.

[Brid]

Even when changing to silicone brake/clutch fluid, it is recommended to change the rubber cups first, as well as thoroughly clean out all pipes & components, as traces of the old brake fluid can give issues.

I used to supply silicone brake fluid (DOT5), and the manufacturer claims are that it never needs replacing, as it does not absorb water (as DOT 3 & 4 do). In my view it is far superior & of course doesn't affect paint work. Dear? Bloody oath!

[richard4u2]

Sure will, tried some once as an emergency stopgap. Had to renew all the rubber cups and seals in the m/cyl. Bob
was told to use water as an emergency then flush asap

[rick130]

was told to use water as an emergency then flush asap

Ditto.

AFAIK brake fluid and therefore clutch system seals and cups are made from Ethylene Propylene Rubber or EPDM/EPM and are NOT compatible with any mineral based fluids at all.

[rick130]

[snip]

I used to supply silicone brake fluid (DOT5), and the manufacturer claims are that it never needs replacing, as it does not absorb water (as DOT 3 & 4 do). In my view it is far superior & of course doesn't affect paint work. Dear? Bloody oath!

I'll pass thanks ;)

There's a reason why silicon based brake fluids are never used in motorsport, the small (or very large for a driver) issue of compressibility.

DOT 5 fluids compress dreadfully (compared to conventional fluids) and so make braking very inconsistent.
I'm sure there are applications that they are worthwhile, but IMO normal car/truck brake systems aren't one of them.

No race brake fluid manufacturer uses a silicon based fluid, they are all ether glycols (most) or silicon ester (the best and only a few and not to be confused with silicon DOT5 fluids) and are totally compatible with each other, unlike silicon brake fluids which as you say, must be used alone.

The brake fluid by which all others are judged in terms of dry and wet boiling point and compressibility, Castrol SRF, used to retail for around $98/litre back in the day. God only knows what it retails for now.

[blackbuttdisco]

I have been using silicon fluid for over 25 years and will not use anything else. Only problem I have had is some rubber seals swell up. There is only one way to tell which rubber is good and that is to soak the rubbers in a small jar over night and see if they swell. This was the advice I received from a manager of PBR in the 70's when he supplied me with a set of front disc brakes for my S2A. They are still working, even if I leave it parked for 18months. No corrosion either with the silicon fluid. We have 9 cars in the family, all with silicon fluid and that includes a 95 D1. Its not cheap, but in the long run I think it is a better way to go, if you are keeping the car for a long time. On the bottle it says not suitable for ABS, the bloke I bought it off said none wants to pay $50,000 to get it tested and okayed.

[rick130]

[snip]
On the bottle it says not suitable for ABS, the bloke I bought it off said none wants to pay $50,000 to get it tested and okayed.

No, it's the compressibility issue, it wouldn't pass. ;)

Glycol ether fluids aren't a problem if regularly (two yearly) flushed either.
That's their only downside, they are hygroscopic and so need to be flushed so it's a waste, but most people are changing there engine oil every six months or so too.

[LOVEMYRANGIE]

Conventional seals (and probably hoses) will be chemically attacked by hydraulic oils and will fail quite rapidly.

A good example of the problem is given by Citroens. Up until 1967 the very elaborate hydraulic system on Citroen cars used a special fluid (LHS2) that was effectively the same as heavy duty brake fluid. It was then replaced on new vehicles by a mineral based fluid, (LHM) that is very similar to an automatic transmission fluid. As a result, every rubber component in the system is different - look the same, but different, causing serious problems if the wrong part or the wrong fluid is used. (They tried to minimise this by a change in fluid colour from red to green, with matching changes for parts packaging, and painted bits changes from black to green.)

John

We have a similar thing with the 'SprintShift' in Mercedes Benz cars and trucks. The fluid used is Pentosin, a mineral based fluid but not compatible with anything else. Reservoirs are different colours with a warning attached.
People still don't read.... Mmmmm hoooooooooge repair bill if you can't read.

[Dougal]

We have a similar thing with the 'SprintShift' in Mercedes Benz cars and trucks. The fluid used is Pentosin, a mineral based fluid but not compatible with anything else. Reservoirs are different colours with a warning attached.
People still don't read.... Mmmmm hoooooooooge repair bill if you can't read.

The wet disc brakes inside machinery axles are the same. Use DOT fluid and it eats it's way out of the brake system, into the front axle oil where it eats all the disc packs and every other axle seal.:(

I hate to think how much that mistake cost them. At least on a telehandler the front axle is easy to get to.

[rick130]

We have a similar thing with the 'SprintShift' in Mercedes Benz cars and trucks. The fluid used is Pentosin, a mineral based fluid but not compatible with anything else. Reservoirs are different colours with a warning attached.
People still don't read.... Mmmmm hoooooooooge repair bill if you can't read.


Which Pentosin ? CHF11-S ?

Pentosin is a German oil company like and competitor to Fuchs, the CHF11-S is used in quite a few Euro vehicles for PS, suspension, etc.
Not sure what so 'special' about it, but Fuchs apparently have a cross with it, Fuchs TITAN ZH 4300 B which has the same MB and VW approvals.

[LOVEMYRANGIE]

Which Pentosin ? CHF11-S ?

Pentosin is a German oil company like and competitor to Fuchs, the CHF11-S is used in quite a few Euro vehicles for PS, suspension, etc.
Not sure what so 'special' about it, but Fuchs apparently have a cross with it, Fuchs TITAN ZH 4300 B which has the same MB and VW approvals.

No one seems to know!! It comes in a MB bottle and is marked "Multigrade Oil". Theres no spec on the bottles!
Part number off the top of my head is A001 989 24 03.

VW approvals are exactly the same because the Krafters are actually made by Mercedes Benz! They come off the same base production lines.

Its only used for the hydraulic shift control and clutch actuation, not gearbox lubrication.

Cheers

Andrew

[Johnno1969]

A little bit of a digression here, but still on basically the same topic.... I remember once reading that if all the clutch or brake fluid was lost in the field, a mixture of vegetable oil and methylated spirits would work as a stop-gap. No idea if that's so. I do seem to remember using vegetable oil very briefly once in such a situation. Or am I imagining that.............?

[rick130]

No one seems to know!! It comes in a MB bottle and is marked "Multigrade Oil". Theres no spec on the bottles!
Part number off the top of my head is A001 989 24 03.

VW approvals are exactly the same because the Krafters are actually made by Mercedes Benz! They come off the same base production lines.

Its only used for the hydraulic shift control and clutch actuation, not gearbox lubrication.

Cheers

Andrew

Cunning bastages !

Here's some tech data in PDF's.

The CHF11-S would be the ultimate PS or DII ACE fluid looking at the specs.
It's the right colour too :D


[edit] did a quick google and it looks like the Pentosin CHF 11-S/Fuchs Titan ZH4300 B is the spec fluid for the Sprintshift, meets MB 345.0 spec. and appears to match your part #.

I'd contact Fuchs here and ask, might save the dealership and customers a few $.

[ps edit] looks like Penrite import an equivalent fluid called SSF, (orange colour) that meets the Citroen CIT 99 7969 (HYDRAactive 3) spec as well as the MB spec.
Note it says 'meets', it doesn't say 'approved' ;)

[JDNSW]

A little bit of a digression here, but still on basically the same topic.... I remember once reading that if all the clutch or brake fluid was lost in the field, a mixture of vegetable oil and methylated spirits would work as a stop-gap. No idea if that's so. I do seem to remember using vegetable oil very briefly once in such a situation. Or am I imagining that.............?

Vegetable oil should not damage the seals, nor should methylated spirits - you can use it to clean brake parts. But for brake use, I don't think either has an adequate boiling point, and vegetable oils tend to oxidise and go sticky pretty quickly, so other than for very temporary use in a clutch system you would have a bit of a cleanup job.

John

[LOVEMYRANGIE]

Vegetable oil should not damage the seals, nor should methylated spirits - you can use it to clean brake parts. But for brake use, I don't think either has an adequate boiling point, and vegetable oils tend to oxidise and go sticky pretty quickly, so other than for very temporary use in a clutch system you would have a bit of a cleanup job.

John

Mixing mineral and veg based oils results in the two forming a gum that will bind everything up.
Same thing as using Bean oil in a two stroke engine, if you change oil from one to the other, it requires a full stripdown and wash of the engine before you can change. You need to assemble again with the oil your going to use in it.
Man I love the smell of bean oil......

Cheers

Andrew

[LOVEMYRANGIE]

[edit] did a quick google and it looks like the Pentosin CHF 11-S/Fuchs Titan ZH4300 B is the spec fluid for the Sprintshift, meets MB 345.0 spec. and appears to match your part #.

I'd contact Fuchs here and ask, might save the dealership and customers a few $.

[

Gives us an option! Might look further into it. Our main oil contract based on OEM requirements as a dealer is to stock and use Mobil for all MB vehicles or specified fluid i.e. Pentosin.
Castrol Tection is used as the alternative.

I've always been keen to try Fuchs, but while I get my Delvac synthetic at cost price, no real need to change!

Cheers

Andrew

[Brid]

Just remembered something relevant here...i bought a 2nd hand 2 tonne dump truck (those 4x4 centre articulated construction things). It was a Chinese import and the brake fluid used was some sort of oil base...not miscible with water at all! Don't know if it was mineral or synthetic...I'd guess it would have been a special synthetic, and presumably one that didn't expand with increased temperature.

I have an impression from a few other experiences that a lot of top end "specialty" synthetic oils are used in China.

Got any ideas on that Rick130?

Regards
Brid

[rick130]

Just remembered something relevant here...i bought a 2nd hand 2 tonne dump truck (those 4x4 centre articulated construction things). It was a Chinese import and the brake fluid used was some sort of oil base...not miscible with water at all! Don't know if it was mineral or synthetic...I'd guess it would have been a special synthetic, and presumably one that didn't expand with increased temperature.

I have an impression from a few other experiences that a lot of top end "specialty" synthetic oils are used in China.

Got any ideas on that Rick130?

Regards
Brid

I have no idea Brid :confused:

It wasn't just what they used in the hydraulics, was it ?
That'd save on servicing and inventory and is pretty common in off road/ag stuff.

eg. maybe even a Chinese version of something like Citröen's LHM Plus ?
That's used for hydraulics and brakes.
Apparently that is specced in quite a bit of stuff, ie. New Holland, Iveco, Massey Fergusson, etc.