Golden LHM?

[CitroJim]

Comma LHM is not very green either, certainly not the neon green of pukka Total stuff..

[steelcityuk]

When I read the title of the thread I thought it must be Hydroflush. It may not be but how could you find out without analysis.

Steve.

[SwissSPEC]

If its hydraflush, it kinda goes a cloudy colour with all the muck in it, old lhm seems quite clear when it goes golden if that portion of the oil has remained relatively uncontaminated.

[Old-Guy]

I can guarantee that the clear golden LHM pictured in the Wiki being syphoned out of of the Green Lady last week was old Delphi LHM+, uncontaminated by any other fluid.

The history is that in September 2008, I drained the hydraulic system as well as is possible, cleaned the filters and reservoir thoroughly, replaced all 6 spheres and bled the brake lines until clear bright green LHM flowed. I bought another 5L of Delphi LHM+ a few years later when I overhauled the rear brakes. Most of this was subsequently used in the VSX that we ran for a year.

Last week, there was next to none of that previous can of LHM left, so I only used fresh Delphi LHM+ from a new can to refill the system. The fluid that came out of the front brake lines initially was brownish and dirty - 7 years-old, and subjected to a fair amount of heat. Including thorough bleeding, I used about 4½L of new LHM in total. The HP pump weeps slightly but the remaining ½L should last another year. If it starts to go faster, I suppose I'll have to change the offending 'O' rings.

While LHM doesn't move much in the brake lines so long as the pads aren't changed, dissolved gases and adsorbed water will, over time, migrate throughout the hydraulic system by osmosis. In contrast, LHM in the suspension and steering (particularly the latter) is constantly circulating through the reservoir where it's exposed to the atmosphere. LHM gets quite hot as a result being compressed, as does the considerable volume of air above it in the reservoir which expands hugely. When the car is parked overnight, this air contracts to a fraction of its hot volume, sucking in a load of cool, moist, fresh air.

I'll see if I can get some information from Delphi on what causes LHM to change colour - my French isn't good enough to ask Total!