The Evolution 25/26 has an excellent hydraulic system for raising the keel. I have not had any problem with mine over the 8 years I have owned my boat and maintenance has been minimal. This leads me to the question what maintenance is required?

If anyone has any information on what maintenance is required, please let me know. For instance, what oil level should be maintained and what type of oil should be used?

I use hydraulic oil, often advertised for hydraulic jacks etc., available from any self-respecting motorist shop. I had mine refurbished by Hamworthy Hydraulics in Poole, and all that was required were some seals, which was quite cheap.