After the Swiss watch, a lock is the finest piece of mechanic. It is amazing how many tiny parts cooperate with a high precision in such a lock. Motorbikes contain several locks, in different shapes, but most of them are cylindrical locks.
Springs (2) push down a series of pins. Each pin consist of a top (3) and bottom (4) part. They all have different dimensions. The pins block the movement of the cylinder (1).
When you insert the right key (5), the pins move against their spring. The cut line (6) between the pins comes opposite to the cylinder. The cylinder can turn.
A thin mineral oil (think about WD40) will provide a smooth movement to the lock. For a short time. These thin oils are often mineral based. Mineral oils tend to form a gum-like residue after some time. This sticks the tiny parts together and block the lock.
Also the use of solid lubricants like PTFE (Teflon®) will cause problems. The solid particles will separate from the oil and they will obstruct a smooth movement.
The only good lubricant is a thin, synthetic lubricating fluid. These do not form a gum, so do not become sticky and do not oxidize. Synthetic fluids are also compatible with all kind of metals. They are not sensible to big temperature differences. As an extra benefit, they do not form fluffy emulsions in the presence of water
Recommended lock oils:
Chose an oil based on PolyAlkylene Glycol (PAG) like used in the KF Lubrifiant Serrure