What kind of oil do I add? I think it’s just a little lowSea Star helm , usually fill hole goes directly into main chamber . I see a mesh reinforced hose , if that hose goes to your fill plug the oil level is good as long as oil is in that hose . Should not use or need oil , unless you have a leak , which will leave a puddle , oil spot under it . The two main items that might leak are the steering wheel shaft where it goes into helm and the rudder / outdrive cylinder around the push pull shaft .
You state the steering was getting " hard " . Usually when low on oil in this system it is just the opposite as you have air in the system and it might take twice as many revolutions of the wheel.to move the rudder. I would isolate the issue by unhooking the rudder/ outdrive ,motor ,from the hydraulic coupler and see if the rudder etc. move freely . Then see if the ram is moving freely , not jerky in motion .
See post # 5 . If your low on oil you have a leak . And if your real low , air will have entered the system , which means bleeding the air out . They sell a hose ( on- line or maybe on this site , around 30.00 ) that goes on the two relief valves on the steering cylinder , this eliminates about 2-3 hours of " normal " bleeding . I recommend buying one . Again , low oil usually does not translate to lumpy or hard steering in a Sea Star setup. And if it's hard to turn , follow my advice on isolating the steering helm from the rudder or outdrive . I purchased a boat that had hard steering . So bad that it took two hands to move the wheel . I was lucky to move either rudder with a 3' pry bar . The rudder shafts had all sorts of tar and crap stuck on the shaft that required me to drop them and sand off the deposition. Worked excellent after that .What kind of oil do I add? I think it’s just a little low