Of LDS and LHM

[cachaciero]

For various reasons I have had cause to investigate a little further on the subject of LHM / LDS mainly because in talking to a recommended independent Citroen specialist about a problem I have he suggested first step would be to flush the system with Hydraflush.... yes I can hear the gasps from around the land .

BUT with the problems I have maybe not so silly. Anyway it was enough to research a little bit more on the question of why not LHM in a C5.

Examination of the specs such as I have found for LDS and LHM reveal that in all the major quoted characteristics they are the same the difference being the obvious one of a mineral base v a synthetic base even the PSA specification numbers are near identical the only difference being the letter prefix B for LHM S for LDS.

As far as I can see on my C5 all the rubber components are "Green coded" for LHM so no problem there.

The biggest benefit that synthetics appear to bring is the ability to run at higher temperatures without breaking down yet on the C5 given that the hydraulics don't do brakes that wouldn't appear to be a significant benefit, however there is a caveat on H3+ plus cars as regards high temperatures and that is the front stiffness regulator which is close to the exhaust and I believe may get significantly warm.

So what can we say, well LHM we know does break down to some degree and can form sticky deposits and varnish over time which is why a period of running on hydra flush can be so benefiicial to LHM cars in that it dissolves and removes the crud which ends up in the filters which are reasonably accesible for cleaning.
There in lies the heart of the problem as regards LHM on a C5 the C5 does have filters quite fine filters but they arn't easily accessible for cleaning.
Now the implications are that LDS does not break down so easily as LHM the oil in theory has an easier life thus no varnishing minimal crud and thus filters will not block up over the life of the car thus no need for access to clean the filters.
It is because LHM will breakdown over a period of time and produce solid by products that will get caught by the filters that it is probably not good to use in a C5 for any significant period.

However I suspect that substituting LHM for LDS in an LHM system may well bring benefits to LHM systems, now I bet not many have thought of that

Which brings me to my problem and dilemma. My car is an H3+ and the front suspension is permanently in hard / semi hard mode. After much work and elimination I came to the conclusion that the spool valve in the stiffness regulator has a weak spring until I talked to this guy that suggested it might be stuck and the first course of action he would do would be to flush it with hydra flush.
Now because the front stiffness regulator is positioned so close to the exhaust I would imagine that it could get quite hot so oil breakdown and varnishing is maybe a real possibility.

Getting at this thing is a pig of a job particularly if you don't have a ramp so taking it off "just to see" is not really an option not sure just how easy they are to dismantle anyway don't even know if it's possible.

Cost of a new regulator is £174.00 from Citroen 5 Litres of Hydraflush is £30.00 is part of the dilemma the other part is that if there is crude / varnish in parts of the system and hydra flush releases it into the filters is that going to give me a problem?

What else have I discovered? well LDS is the same oil recommended for many power steering systems under different names and that at least one manufacturer / supplier produces such an oil which is green in colour a recipe for confusion

cachaciero

[JohnD]

one manufacturer produces such an oil which is green in colour a recipe for confusion

Seem to recall a few weeks ago someone on the forum buying what he said was green LDS.

[addo]

Wow! I was under the complete misapprehension that LDS shared more genes with DOT4, and in a genuine emergency would have tried to substitute this.

This is easily "Lesson of the Month" - if not more significant.

[mooseshaver]

Seem to recall a few weeks ago someone on the forum buying what he said was green LDS.

Was that me with my Comma stuff? Its green. And when the stuff is added to the tank as a top up you get brown liquid!
I am assured it is correct and its just a dye that is added to select colour, it is confusing.
My local motor factor type place now does proper Total LDS so I have bought that this time.

Ben

[cachaciero]

Was that me with my Comma stuff? Its green. And when the stuff is added to the tank as a top up you get brown liquid!
I am assured it is correct and its just a dye that is added to select colour, it is confusing.
My local motor factor type place now does proper Total LDS so I have bought that this time.

Ben

The one I was looking at was from CarLube so that's two different names (though possibly the same product) in green.

I guess the best way of describing these would be equivalent to LDS rather than LDS because as far as I can see the actual LDS spec specifies that the colour be orange. See spec sheets for both Total LDS and Eurol LDS.

cacahciero

[cachaciero]

Quoted directly from the Total LDS safety sheet:-

2. COMPOSITION/INFORMATION ON INGREDIENTS
PREPARATION
Chemical nature : The product is made from refined mineral base oils and synthetic oils
(Polyalphaolefins).
in which the polycyclic aromatic hydrocarbons (PCA or PAH) content, measured by
IP 346, is less than 3%

So it's not even a pure synthetic base.

It goes on to say that the mineral component of the base will evaporate over time when exposed to air.

cachaciero

[mooseshaver]

It goes on to say that the mineral component of the base will evaporate over time when exposed to air.

cachaciero

So don't take the top off the tank? If its a sealed system with no leaks, then it should not evaporate, so the fluid should not need changed even with age?
I remember when I asked for my previous C5 to have the suspension serviced (supposed to be a fluid change) the Dealers had never done it because noone round here bothered to.

[Xaccers]

I remember when I asked for my previous C5 to have the suspension serviced (supposed to be a fluid change) the Dealers had never done it because noone round here bothered to.

If you asked the garages the same about Xantias and BXs, and they gave you an honest answer, they'd probably say the same judging by the number of 10 year old Xantias I've seen with "full citroen service history" and filthy LHM!
Similarly with accumulator and antisink spheres.

Garages give bonuses to those who are able to get more jobs through in a day. You may be charged 3 hours for a job that only took them 45 minutes if they cut corners and used tricks of the trade (the problem comes when like a guy I know, they cut the corners more than they should). Changing extra spheres and hydraulic fluid which won't be noticed by most owners costs time so can be missed (of course the customer may be charged for it still!).

[addo]

There's also the possibility with some service operations, of non-textbook ways that are quicker and work just as well.

I was told a ripper story about a C6 that needed new front spheres (presumably due to their sacrificial nature in a harsh jolt) - it was temporarily fitted with green ones by the repairing dealer!

[cachaciero]

So don't take the top off the tank? If its a sealed system with no leaks, then it should not evaporate, so the fluid should not need changed even with age?
I remember when I asked for my previous C5 to have the suspension serviced (supposed to be a fluid change) the Dealers had never done it because noone round here bothered to.

Yes quite but what I was trying to find an answer to, amongst other things is why should you dispose of an opened bottle of LDS after a couple of weeks and so far I have not found a satisfactory answer.
Nothing will evaporate from a part used bottle if the cap has been re-fitted, at normal room temperature I doubt that anything would evaporate anyway. Water absorbtion? again as far as I understand it the oil is NOT hygroscopic so that's not a problem so what else is there? oxydization? I would only expect that at elevated temperatures .
So as far as I can see the instruction to dispose of part used bottles is BS designed to increase PSA's profit margins.
In-fact now I know that LDS is actually semi synthetic rather than full synthetic I am beginning to think that the whole LDS issue may be smoke and mirrors and that LHM may be more than satisfactory in a C5.

It would be nice to know why other manufacturers specify an LDS type fluid for their steering systems, if I could find a good technical explanation for that that may read across to C5 I would be happier.

I suggest given that the amount of work that LDS does is less than in an LHM car then changing the oil on a regular basis is probably not worth doing, particularly as most / all of the filters in the system cannot be cleaned / changed without a major strip down of the BHI, and even then I'm not sure.

cachaciero

[Paul-R]

Nothing will evaporate from a part used bottle if the cap has been re-fitted

Which begs the point - why is the cap of the reservoir so much more efficient han the cap of the bottle?

As you do, I suspect not.

[dnsey]

As with photographic developers, which oxidise quite aggressively, I'd suggest adding something like (clean) marbles to a part-used bottle of LDS, in order to bring the level back to the brim. That way there's no significant amount of air above the fluid to encourage oxidation or water absorbtion.

As regards the change from LHM, I think the reason may be simply that LHM is a propriatory fluid, but LDS is, as has been said, a fairly commonplace steering system fluid in reality, so is probably cheaper (from industrial suppliers), and easier to source locally in export markets.

[cachaciero]

As with photographic developers, which oxidise quite aggressively, I'd suggest adding something like (clean) marbles to a part-used bottle of LDS, in order to bring the level back to the brim. That way there's no significant amount of air above the fluid to encourage oxidation or water absorbtion.

A practical solution to keeping air in the bottle to minimum, mind I lost my marbles long ago t but I don't believe that LDS does oxidise quickly if at all, at least at normal room temperatures.

As regards the change from LHM, I think the reason may be simply that LHM is a propriatory fluid, but LDS is, as has been said, a fairly commonplace steering system fluid in reality, so is probably cheaper (from industrial suppliers), and easier to source locally in export markets.

Well that's an interesting take on the situation and may well have some bearing on it. Would be interesting to know if LDS came first and was then adopted by other manufacturers for steering boxes or if the oil was first speced for steering boxes and subsequently adopted by PSA as LDS.

cachaciero