If you have a SPEC boot, you are one lucky guy!
The boot dates from silicone days. Only a few of us fill the regs, any more, and I use Tribolube 66.
Instructions: Insert the HP oring, bushing and circlip into the reg body. Mount the first shim and spring on the piston. Add a piston bullet. Using a syringe, carefully fill EVERY void between the piston shaft and the coils of the spring. Then continue coating the outside of the spring until you have a short sausage with ZERO air pockets. Ensure the diameter of this sausage is equal to the inside diameter of the reg body. Add the additional shim in the recess in the body. Use the syringe to lay in a line of grease (silicone, Tribolube or Christolube) in the recess where the spring will fit. With the body held over the piston spring combo, carefully slide the piston, spring and bullet up into the reg body. Grease will ooze out of the space between the body and piston head.
With the piston held up inside the reg body, remove the bullet. Invert the assembly and inspect the area just inside of the piston head. If grease is not flush with the piston head, carefully syringe additional grease into the crack.
Making sure the Intermediate pressure side of the piston is free of grease, carefully screw on the housing cap. As you screw it down, grease will come of of each ambient hole. Wipe it off and screw another half turn until the cap is fully in place. Once the cap is screwed down, slide the SPEC boot into the recess. Using the syringe, squeeze a ring of grease around the entire inside circumference of the boot, and massage it gently, listening for little pops as any trapped air slips out of the boot. Pressurize the system, at which point additional grease will ooze out of the boot edges.
Massage the boot again until it is flat. If additional bubbles seem trapped, slide the syringe end under the boot and squirt a little more in and massage the boot flat with the surface of the reg.
Depressurize the reg, and the boot should suck in slightly. Done.
It's messy, especially with silicone! But with practice, the wasted total grease is less than 2 cc.
If you don't have a boot, you can actually use silicone by itself, as the bubbles that are created as grease oozes out and is sucked back in are right under the ambient holes, and most of the chamber is protected from salt water. Christolube is too thin to do this with.
