Today I added the brake fluid to the hand brake system and gear oil to the reduction drive. The hydraulic disc brakes are Black Max made by Free Bird Innovations. They call for using ATF rather than brake fluid. The hand brake cylinder has a fill plug and the disc caliper has a bleed screw. Pretty standard process to fill and bleed the lines. The propeller speed reduction gearbox calls for using 85W-140 gear oil. The vent, drain, and two fill level plugs are setup for both upright and inverted engine installations. Vent plug on top, drain plug on bottom, and use the lower fill level plug. Simply remove the vent plug and the lower fill level plug and add gear oil until it starts seeping out the fill level hole.