MoYu cubes often arrive feeling dry and slightly sandy. MoYu Lube No.1 is the answer to that. It is a silicone-based lubricant that smooths the turning and adds a little control without speeding the cube up.
A few drops of MoYu Lube No.1 in the mechanism is enough. Used sparingly it takes the scratchiness out and leaves the turning feel intact. Used heavily it goes gummy and takes a great many solves to work out again, so start light.
It suits any brand of cube, not only MoYu. For a faster feel rather than a smoother one, MoYu Lube No.2 5ml is the water-based alternative.
