Traxxas Differential Oil 50K weight is a high-viscosity, sticky, silicone-based lubricant originally created for use in remote control vehicles, but it has also become popular for lubricating twisty puzzles.
The lubricant comes in a convenient-use syringe with a twist-off lock cap. The syringe form is particularly useful for allowing the lube to be readily dispensed regardless of how much lube is remaining. It also comes with a green applicator tip, which can be used to apply the lube into hard to reach places.
This lubricant can be applied to both the core and pieces of a cube. However, we would recommend using the lube sparingly (just a few drops at a time) to avoid gumming up the cube too much.
Disclaimer: Although Traxxas 50K lube is safe to touch, please do not ingest it, set it on fire, or expose it to extremely high temperatures.