Replacement is necessary but how often is the question. Nothing in the manual obviously - probably specified in one of those long since forgotten BMC service bulletins....................
The stuff out of Ken's Elf had the appearance and consistency of octopus semen

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

And the obvious question there is "how do you know what octopus semen looks like ???"

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yep, upping the ratio in favour of the Ethylene Glycol, will make the ride a little firmer as it is higher viscosity.

The Cooper S came out with exactly the same hydro fluid as the rest of the hydro cars, the valving inside the displacers is what gave a stiffer ride.

Try it out with a 50/50 mix first, this is still a higher viscosity than the original fluid.

On a side note, the original fluid had the alcohol content to act as a rust inhibitor, and then legally they had to add the bittering agent, which is the one with the long name!


Cheers
matt

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68 Deluxe.... it's shiny..... I like shiny!!

Sports 850 wrote:

And the obvious question there is "how do you know what octopus semen looks like ???"

Vivid imagination - and inspired by my children who compare the mayonaise on Big Macs with seagull's semen!

_________________
1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

I read somewhere that the bittering agent was to stop the workers on the assembly line drinking it, although that may well be an urban myth.

I heard that too! Although it was actually illegal to sell "alcohol" in that form without having the agent added. Moonshine anyone?

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68 Deluxe.... it's shiny..... I like shiny!!

Every couple of years would be a good idea. The stuff in my system had been there for about 30 years I reckon! Nasty brown sloppy stuff it was.

Nice green colour now!!

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68 Deluxe.... it's shiny..... I like shiny!!

I guess if you were really keen to tempt fate, you could try using the 'LHM' fluid that hydropneumatic Citroens use in their suspension systems. It IS a mineral oil (LHM stands for Liquide Hydraulique Mineral as far as I know) so It would probably have better lubrication properties than the BMC hydrolastic fluid. . .maybe.
Should be safe with rubber components. . .it certainly is in Citroens.
As it is non-hydroscopic, you might run into the same problem as when you use silicone brake fluids. . .any water in the system pools in the lowest part of the pipework, separate from the oil fraction of the fluid and rots metal lines away extremely effectively.
I reckon I'd stick with a glycol/water mix. . .

Don't try the Citroen fluid, it will stuff things.

The Cooper S has a thicker spring and that is what gives it the stiffer ride.

The stuff that everyone claims is "Genuine Fluid" is not genuine fluid. (I mean the stuff in Morris tins)

Penrite used to sell Hydrolastic fluid a few years back but they stopped making it. They stuck their recipe on the website, 50% antifreeze 50% water.

I re-use old fluid. After it sits for a while the sediment falls to the bottom and then I filter it. Looks and smells as good as new!

Pete...Ray knew of a Chemist who worked for BMC and used to brew up concoctions for the Rally Cars etc....I think he managed to get some of the formulas...ask him next time you see him

[edit: come to think of it I know a fella who was deep inside BMC and knows his chemistry...oil axe him!! ]

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"Show me the Mini!"

Check this site for the official recipe, both OZ and UK.
http://austin1800.homestead.com/page11.html
There was also a competition version of the hydro fluid available early on. My first S, circa 66, had a loose leaf insert in the owners handbook which mentioned Competition grade hydro fluid, changed ignition timing for super grade fuel instead of 100 Octane, and alternative distributor advance weight springs for permanent use of super fuel.
Presumably the competition grade fluid would be thicker with a higher viscosity index.

RonR

Thanks one & all for your comments. A wealth of expertise out there. Will stick with the ethylene glycol/distilled water & experiment with various concentrations

_________________
1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.