There are two things going on in this photo to take note of. First, notice the lump of black garbage in the bottom of the case. That's metal that has collected to a magnetic disk glued to the case. Cook says it is impossible to clean properly, so he just knocks it out with a chisel and throws it away. If you maintain your transmission properly, you won't need the magnet anyway. Second, it is difficult to tell here, but that muddy mess you see has more water in it than oil and is the reason some of the gears on the main shaft are ruined.

When installing the gears and synchronizer hubs back on the cluster shaft, Cook uses a lithium-based paste for lubrication. It's thick enough that it will still be in place no matter how long the transmission sits before its first use.

Jim Cook Racing Transmissions