I just installed a ST-6000 autopilot, and have become an expert on bleeding the steering system.
Get instructions from the Teleflex/Seastar web site. They're pretty good.
Then, the reccomended oil is Teleflex oil ($12.50/qt, $55/gal), or (from Seastar site) Mil-H5606C ($24/gal at an airplane supply,)
Hand/manual bleeding is a pain, since the volume of the pump is small thus the velocity is small, and the hydraulic lines go up and down. However it works. Get some 5/16" plastic hose for the bleed fittings at the engine cylinder, and you can reuse the oil (put the output into a CLEAN can.) Teleflex also sells ($12,) a filler kit, which is a 1/4" plastic pipe fitting, a piece of plastic tube, and a cap with a spout on it. Worth the money to me, buy easy enough to make one. Don't forget the push pin that they supply.
Takes two people; a significant other to hold the bleed oil supply up at the wheel/pump and turn the wheel, and you to loosen the bleed fittings on the cylinder (or vice versa.) With a quart supply bottle, one can only bleed a quart through at a time.
The factory has a power bleeder. Found one on sale for only $500. Back to hand bleeding.
Sorry youall had to read this, but I had to do it.
Boris