Is there any kind of silicone grease that is better or worse for using on the threads of a No-Nonsense pen, to use it as an eyedrop filler. Is silicone lubricant the same thing? Recommended brands? Thanks.

Here's a search done for silicone grease. A few threads contain interesting discussions.

http://www.fountainpennetwork.com/forum/in...silicone+grease

The short story:
Most on line pen repair or supply places have it: Pendemonium, Tryphon, etc.
Other sources include:
Dive shops - silicon lube for o-rings in SCUBA system,
Auto supply - silicon lube for disk brakes
Food supply industry - food grade silicone grease
Radio Shack - heat sink grease (silicone)
Plumbing supply - faucet grease (Moen is a brand I use)

Some have different consistencies - the plumbing is a little thicker, and for your application would work just fine. You can also use a plumbers wax usually sold in a ring for this application. I have done a number and never had a problem.
the wax is very inexpensive.

Regards,

Gerry

Silicone lubricant might be the same thing. Best to buy the recommended ones, especially the diving equipment kind or that sold by a pen repair person. The reason is not the silicone, but what else can be in the grease that might harm pen parts. (Automotive grease especially could have additives that might not be good for pens.)