LHM is "Liquide Hydraulic Minerale" I believe, Excuse my French, Basically the green fluid for citroens and others. Since the system on the cabrio is not used for braking I would go with ordinary hydraulic oil, much cheaper and if you have a friend in the plant business you should get some no bother, I'd imagine a litre is about enough. If you were local to me I have plenty of LHM but not worth the postage.