Ray, I suspect you will need to purge the steering hydraulics when you top off but the procedure varies based on which unit you have. Teleflex is the most likely maker of your steering system and it would be best to identify the exact model you have. Here is a link to the Teleflex hydraulic steering manuals: http://www.teleflexmarine.com/suppo...nuals/hydraulic-installation-manuals-inboard/. Hopefully the one you need will be there.
BTW, I don't think trim tab units normally consume fluid so I suspect you have a leak.
BTW, I don't think trim tab units normally consume fluid so I suspect you have a leak.