LDS v LHM

[Vasco826]

Hello, I'm new here having recently come back to the Citroen world

I've recently bought a lovely 2009 C5 Exclusive Tourer but it seems to have a few issues I wasn't aware of when I bought it - despite full MOT and seemingly really good condition with around 120k miles on the clock

Main problem was leaking front struts, although I understood they were changed less than 2 years ago and the car has only done 2000 miles or so since. Having sourced replacement OE struts the garage doing the job of changing them tells me that the car has been filled, or at least topped up, with LHM not LDS, judging by the colour of the fluid when draining for the repairs.

Could this have trashed the seals on the struts, but perhaps more to the point, what other damage is the use of the wrong fluid likely to have done, if any. I know mixing red and green in my old DS21 was a real issue wrt to seals perishing etc, is it the same with LHM and LDS?

Any advice most welcome please. Thank you

[RichardW]

Unlikely, the front strut return hoses on mk 1 and 2 C5s (LDS) were the same part number as the Xantia and BX before (LHM)!

[Kees]

I don't know if you can say this, because the struts of an C5 X7 are totally different and even with LDS they start leaking but not after 2 years....
Greetings,
Kees.

[aerodynamica]

Hi, for what it's worth I put LHM in a glass jar and dropped in an LDS rubber O ring. I did the same with an LHM o ring in a jar of LDS a couple of years ago and left each of them for about two months. I found absolutely no change in either O ring. I didn't see any swelling, softening, hardening or change in colour. Each fluid seemed to remain the same too. I concluded that LHM and LDS fluids are not harmful to each other's system. It was casual observation but I think you'd see a reaction if they were seriously incompatible like in the case of LHS - LHM or Brake fluid.

[GiveMeABreak]

That may be the case in the short term, but Citroen would not of changed the fluid type for no reason and as said LHM is mineral based fluid and LDS is not.

I suspect one could even fill the hydraulic system with chip oil in the short term - but I wouldn't expect the system to last very long.

[citroenguy]

Some power steering fluids, green in colour are PSA S71 2710 classed. The same specification as LDS.
You could simplify it that LDS is just power steering fluid in orange to differentiate from LHM

It is the same P/S fluid as in Vauxhall/Opel, VAG, Volvo etc...
https://www.mpmoil.com/products/50000/p ... -synthetic

It is very confusing for a Citroën mechanic if someone has filled it with that

[Stickyfinger]

It is the same P/S fluid as in Vauxhall/Opel, VAG, Volvo etc...
https://www.mpmoil.com/products/50000/p ... -synthetic

£55 per Ltr.....

LOL


My bet is that LDS was "developed" to be a fluid that was compatible across the range of cars and was a unique "need" for PSA cars (even when labled under a different name by other plastic badge cars.

LDS Spec

LHM Spec

[citroenguy]

It is the same P/S fluid as in Vauxhall/Opel, VAG, Volvo etc...
https://www.mpmoil.com/products/50000/p ... -synthetic

£55 per Ltr.....

LOL


My bet is that LDS was "developed" to be a fluid that was compatible across the range of cars and was a unique "need" for PSA cars (even when labled under a different name by other plastic badge cars.

LDS Spec


LHM Spec

It is much cheaper "off brand" than LDS here in Sweden and easier to find in a i store (car supermarket ish) ~19£ vs LDS that is 30-40£ a litre at the motorfactors/dealer.
LDS can be had much cheaper online though.

LDS and Fluide DA (Direction assiste) are used in basically all PSA cars with electro-hydraulic power steering. Same spec PSA S71 2710, just a different bottle

[GiveMeABreak]

I note that those are only the temp and viscosity characteristics, but doesn't have anything about the actual oil composition...

Here's some further info for the 2 types from a particlular supplier:

LHM Plus

LDS

[PaulC5]

I can never understand why somebody would try to save a few pounds and not use the correct fluids in a system that can cost hundreds/thousands to repair if the fluid is not right. The correct fluid should be seen as an investment to save future costs. We had a Saab 9-5 which needed a new steering rack after all its seals failed, apparently since it had the wrong fluid in it shown by it not being the colour of the Saab specified one. We had only bought it a few months earlier and fortunately had a breakdown warranty but they would only pay for a reconditioned one so I had to pay the rest to get a new one.

[Jay-Bruce]

I've looked at the MSDS sheets for these oils, and posted the links to them from the total website before, but my take home from them is that chemically they are "within spitting distance" of each other, with LDS having less noxious additives than LHM. I'd wager that a comparison of LHM to LDS is more akin to Dexron II --> Dexron III than comparing LHM --> Dot IV brake fluid. LDS seals are as far as I can tell "Fluororubber" which is pretty forgiving, and more robust than the materials used in LHM systems which IIRC were Buna-N (or was it Nitrile?) and Graeme's jamjar lab test seems to have proven the relative interchangeability of these fluids that my archaeological study of the specs suggests would be the case.

Although, for obvious liability, and maybe even safety reasons, the FCF can never officially recommend running the wrong fluid, I believe we can downgrade the severity of mixing these fluids from a "doomsday" to a "minor oopsies".

[Stickyfinger]

I can never understand why somebody would try to save a few pounds and not use the correct fluids...............

Nor do I.....but I would use an identical product that was half the price because it had a different name on the bottle...LDS/Fluide DA for example