Flushing the hydraulic system

There is a product called Hydraurinçage (sometimes also called HydraFlush, the French name is pronounced as \id-ro-ra[n]-sa'zh\ or, more precisely, using the IPA phonetic symbols: ɪdrɔrɛŋ'sɑ:ʒ). It's a special cleaning liquid manufactured by Total, orange in color; your nearest Citroën dealer is sure to have it on stock. The price is more or less the same as that of the regular LHM.