We carry some spare fluid on Old Spice just in case but otherwise never had a problem in 7 years with Hydraulics. Biggest headache is bleeding the system the first time as the stuff goes everywhere, oh yes and working out which hose goes on which side. Yep got it wrong and ended up with the engine turning the opposite way. Did notice that a drop of fuild will leak out in hot weather as the metal steering wheel pump warms up and the fluid expands and blows out, but its so minor a tea spoon full would top up the system at the end of the season. The girls like it too as its easy to steer a rib with Hydrualic steering and there is no feed back with you have a single engine.