Definitely only use LHM fluid for the hyds. To check the level, stop your Xantia on level ground, leave the engine running, select the ride height to maximum (a forwards backwards lever between the drivers seat and the handbrake - move it fully back), wait for the car to raise fully up, open the bonnet and support, look at the black plastic reservoir on the passenger side, top rear of the engine bay. There should be a bulb on top of it with a disc on a stick inside. This indicates the level. It should be indicating between the 2 marks on the bulb. Simply pull the cap to remove and pour more in if required. Once finished topping it up, replace the cap, close the bonnet, select ride height back to neutral (centre position) and once car has lowered itself again, drive away or switch off.
Jim Allen
March 2008