Probably a Sea Star system, which you can buy there steering oil , 30ish a quart online . Or you can use any light weight oil #5 ( hydraulic oil like they use for snowplows )and under . Transmission oil will also work. Fill to about a 1/2" below the cap , that's for expansion in the hot weather . Depends on where that oil goes to , could be remote tank under the fill hole , or this directly goes to the helm itself . Picture from behind would help . If you can see oil at the top now , your good to go .