Apparently there's a host of ABSOLUTELY TERRIBLE advice concerning what lubricants can be used with Nerf blasters. Making the wrong choice is likely to result in permanent damage, and even the eventual destruction of your prized plastic possession. DO NOT USE THE SPRAY CANS OF ANY KIND. Any Spray can adhesives are likely to contain petroleum products and solvents in the propellants and those will aggressively damage plastics. Some may even contain alcohol as a thinner.
Ones you should use
1. Silicone - Available in many varieties and applications, and you must select the type that is intended for your use. Certain mixes contain purposed additives or viscosity ratings that could actually hinder performance or potentially damage your Nerf blaster internals.
Get the Silicone GREASE that's available in small tubs. In hardware stores it is usually located near the PVC Solvent Cements.
2. Barium - Harder to find, mostly available from industrial supply. I don't have any personal experience using it myself, but it is used for high-wear applications and in pneumatic control equipment like air cylinders.
3. Dry Teflon pastes - Somewhat expensive but very effective.
Use with caution
1. Lithium - Typically used for bearings this comes as a grease/paste in a variety of specific application options. However any multipurpose lithium grease will work fine so long as it's not one of the varieties with a much thicker blend or too many additives for secondary purposes. The base oil for most "Lithium" Grease is actually mineral oil but the concentration of it is low and the solvent potency of it is low as well. So this one is iffy and depends heavily on which product you purchase because they come in so much variety. The plainer the better.
2. Petroleum Jelly - Pure Petroleum Jelly is compatible with plastics and synthetic rubber, but not advisable for natural rubbers. Avoid any relevant products that include additives for moisturizing (such as chapstick) and be sure that the parts it will be interacting with are chemically compatible.
3. Graphite powder/paste/spray - While it is plastic safe, it is not intended for this type of application. Intended use is for machinery. Also extremely messy. It can work, but isn't advised.
Ones you should not be using under any circumstances.
1. WD-40 - This stuff was NOT DEVELOPED as a lubricant. It primarily is used for water-displacement (where the WD acronym comes from), de-greasing, and rust removal. It will UTTERLY DESTROY O-rings in a fairly short period of time, and will eventually destroy plastics.
2. Vegetable Oil - This is a food product and will eventually start to decompose. You will end up with a bacteria farm inside of your Nerf gun.
3. Mineral Oil - Will penetrate o-rings and cause them to soften and swell. Does the same to any natural or synthetic rubber products.
4. Glycerin based (KY jelly or otherwise) - Also a food product (a sugar) which dries up very quickly and will eventually farm bacteria and make sticky surfaces.
5. "Moly" Grease - These are Mineral Oil based greases. Compatible with plastics, but not compatible with rubber of any type. Their intended application is in ball-bearings.
THE BOTTOM LINE: Just use silicone. Nothing else is intended for this type of application.
Edited by CaptainSlug, 08 July 2016 - 12:45 PM.