Sea Star fluid or equivalent , which I believe is called H5606 . — It is basically aviation hydraulic fluid . — Wear rubber gloves when handling or your skin will peel off for weeks . — ( Dont ask me how I know !!! ) —– Full to the opening . — No drain plug , that Ive found anyway . — Should be good for YEARS in these systems . — Hoss Last edited by BIGCATTER on October 9th, 2015, 7:56 pm, edited 1 time in total.