"Old" LHM standard number, LHM replaceability

(CZ)enda · Post by **(CZ)enda** » Fri Mar 17, 2006 1:37 pm

While I was able to find the number of the applicable PSA standard for LMH+ (PSA B712710), I was unable to find one for the old, "non-plus" LHM.
The thing is that I am trying to find a statement of its properties (viscosity, kinematic viscosity, viscosity index etc.) and compare its specifications with general hydraulic oils, which are easily available at any gas station for about 1/4 - 1/2 of the Total LHM price.
Although general opinion of the local forum is that one of the generic hydraulic oils can be used without any negative impact on the hydraulic system (supposedly tried and proven), I would like to check the data before draining Hydraurincage from my system and topping it up again.
Any ideas where to get the data? Local Total homepage did not help, they have the data available for LHM+ only.
And, back to the real world from the academic one

, what are experiences with running the BX on hydraulic oil other than original (expensive) LHM?
Thanx.

jeremy · Post by **jeremy** » Fri Mar 17, 2006 1:58 pm

I think the general experience is that if you have anything other than LHM in the hydraulic system then the best thing is to get it out as soon as possible, flush the system and refill with LHM.

There have been one or two instances that I recall on Citroen boards of people finding Automatic transmission fluid of some kind in the system - which is considered undesireable as it contains friction modifiers which apparently are considered essential for automatic transmissions. Of course the same stuff is used in most PAS systems without problems and I can't imagine that they need friction modifiers!

It must be remembered that in UK LHM is relatively cheap and much more readily available than specialised hydraulic fluid - and so there is no reason to find an alternative. (Its also much the same price as automatic transmission fluid)

jeremy

DavidRutherford · Post by **DavidRutherford** » Fri Mar 17, 2006 2:18 pm

As far as I know, the only oils that can be used instead of LHM are mineral based ones (a number of hydraulic oils are either synthetic, or vegetable oil based)

On my old "breaker" 19DTR I put a load of engine oil in the LHM tank, as it was very low (leaking) and I needed to move the car. It's now about 50/50 LHM/15w-40. It hasn't damaged any of the rubber parts, but being a higher viscosity has meant that the suspension goes up and down slower and is overdamped, the brakes are a tiny bit slower to react, and the steering is ultra-smoothly-damped, but a little slower.

The other effect seems to be that the car no longer sinks... even after a couple of months of being at maximum height, it shows no signs of sinking at all. I presume this is to do with the oil molecules being larger/longer and not able to leak past seals as easily.

Who needs Anti-sink valves? just put some engine oil in the LHM!*

*May not actually be a good idea. Citroen may know best when it comes to oil specs for their cars.

AlanS · Post by **AlanS** » Fri Mar 17, 2006 10:30 pm

Put a Dot hydraulic fluid in and you'll destroy the entire system if its left in there as it's synthetic (Vege based) whereas LHM is mineral based.
Besides friction enhancers in ATF there are also seal swellers, so obviously anything with rubber in it has to be affected one way or the other.
I understand the yanks have used I think it's silicone in their Cits for years but that would be far and away much more expensive than LHM.
It has been claimed that a "Milspec" (Military specification) 556(?) hydraulic fluid as used in Military aircraft will work, but again it is used in a different set of circumstances in that it doesn't have to cope with suspensions and height correctors and doubts have been cast as to whether or not it contains any lubricating properties, again, something not known of in LHM anyway.
LHM was superceded by LHM+ about the time the active suspensions were being introduced and again it has been suggested that the + version is of a thinner consistency so as to allow it to travel through all the valves etc and allow the hydractive system to react within the desired time frame.
There was a write up on the properties written by a guy in the US which I think Blair Anderson may have had a link to on the "Citroen Connection" but I found it a bit involved and not easy to follow.
We used to have problems accessing LHM here until I contacted Total directly and asked about importing it privateky at which point I was referred to a local distributor who sells it cheaper than I could buy it 20 years ago.
Don't know what Government regs are over your way, but might be worth looking at getting the right stuff and getting it sent across.
There was someone in Holland selling a substitute that was a fair price. May be worth dropping this guy a line and asking the question.

http://www.citroen-andre.com/

Alan S

(CZ)enda · Post by **(CZ)enda** » Sat Mar 18, 2006 10:38 am

The hydraulic oil considered is, of course, mineral. According to the datasheet available from its manufacturer, it is suitable for PAS and hydraulic systems in forklifts etc.
However, decisive factor for staying with LHM was its properties - low viscosity index compared to LHM (meaning its viscosity changes considerably with temperature). Also, its point of flow is at -36°C, while Fuchs LHM is at -54°C, Total LHM+ is at -62°C.
As it is, all thoughts of experimentation are dismissed.

jeremy · Post by **jeremy** » Sat Mar 18, 2006 12:06 pm

I can vouch for the temperature instability of hydraulic oil considered suitable for forklifts - I used to be able to write notes in the time it took for the forks to descend on cold days - bit difficult as the fork control was on the right and I'm right handed but it was better than just sitting there watching it.

It was not only the fault of the oil - early attempts at computerisation and design influence from Porsche probably didn't help either - and produced a machine with manager rather that operator appeal. You must remember that managers buy these things - not the operators - who only use them.

Wonderful things - with regenerative braking - so lift off and it stops - quite nice when you're used to it - except that with control circuit failure - the regenerative braking stops working - and as you are not expecting that to happen your foot is no-where near the brake pedal! Luckily some trailers are heavily constructed!

jeremy

AndersDK · Post by **AndersDK** » Fri Mar 24, 2006 1:58 pm

Hi CZenda - long time no see

You dont have to buy Total branded LHM (plus) ?
Any major oil company have LHM plus in their assortment of oils. And they all apply to the PSA standard. If not - then it would not be an LHM oil.

(CZ)enda · Post by **(CZ)enda** » Sat Mar 25, 2006 10:51 am

Hi, AndersDK - the world of BXers is small, isn't it

.

Yes, I noticed there are Esso, Castrol, Bendix etc. alternatives to Total available, but I was trying to support local manufacturers instead of the nasty supranational companies

(and to save some money in the process

).

Although this approach works very well with engine oils (local 15W40 API SL is 1/3 cheaper than 15W40 Castrol API SG), they do not bother to produce such niche product like LHM.

It will be Total LHM+ then.

Clogzz · Post by **Clogzz** » Sat Mar 25, 2006 12:01 pm

Think you can get LHM from 'New Holland' farming machines.
Looks like LHM+ is used in quite a few farming machines, as listed here:

http://www.aral-lubricants.com/lubrican ... arNum=0283