For older sea cocks, here is the advice I received from GROCO today
The older seacock, SV series DEFINATELY need lubrication.
So...
With the boat in the water,
*1. Install the same 1/8x27 Stainless Steel Zerk fitting into the side of the valve.
*2. Loosen the wing nut
*3. Open the valve. DO NOT DO THIS WITH VALVE CLOSED! Doing so will fill the plug center with grease and when the system becomes active, will pull the grease into the system. Nothing will be lubricated.
*4. Inject a squirt or two of a Non-Petroleuem lubricant, Silicone grease is good, Lithium is next. Do not use standard wheel bearing grease (oil based).
*5. Work the valve back and forth.
*6. Leave the valve in the desired position
*7. Snug the wing-nut to stop any leakage.
With the boat on the hard,
1. loosen the wing nut
2. remove the two 7/16' Head bolts from the face ring.
3. remove the face ring and wiggle, do not force, the plug from the body
4. knock off any high spots or burrs from the plug with emery cloth.
5. slick up the plug with the grease.
6. using steel wool or fine emery cloth, polish the inside of the body of the seacock.
7. Reassemble
8. drop the boat in the water and check for leaks.