A lot of French boats use the lecomble and schmitt systems. Recommended for them is ISO 15 wt oil. ( note ISO 15 wt is much lighter than 15 w engine
oils more inline with 5W)
It's very frustrating to get a correct spec from a manufacturer.
I installed a 7000$ Hydrive system and they wouldn't give me the specification for a commercially available oil. Wanted me to pay the 900$ to airfreight their name brand stuff " specially formulated" in Australia
. I declined their offer and I bought aviation quality ISO 15 wt as that was all I could find close to the specs. I suspect dexron trpe transmission
fluid would have been fine . I found it quite difficult to find light hydraulic oil specified.