Spray lubricants were first introduced to the marketplace in the form of WD-40 for application to all types of light machinery, as a replacement to machine oils that required long-necked cans,. The success of WD-40 encouraged other manufacturers to move into this field, to the point where today there are a number of companies providing spray lubricants.
These spray lubricants are light-weight machine oils, not heavyweight. When referring to oils, lightweight refers to a low viscosity or "watery" oil while heavyweight oils are high viscosity oils, more like molasses. In comparing them to motor oil used for automotive engines, lightweight machine oils are considerably lighter than even 5W30, the lightest of the standard automotive oils.
These oils are mostly designed for lubricating fine and small machinery, such as sewing machines and lock mechanisms (but not the lock itself). The lightweight oil wicks into tight spaces, thoroughly lubricating all parts of the device. As such, it is very good for seeping into the tight spaces between bearing surfaces, providing them with lubrications. They can also be used as penetrating oils, seeping in to loosen rusted or over-tightened bolts and nuts.
Most spray lubricants are petroleum based, although there are a few exceptions. Two of the most important deviations from petroleum are Teflon and silicone, both of which provide excellent lubrication as they are very slippery substances, which other materials will not stick to. Neither Teflon or silicone lubricants should be used in instances where the surfaces will later be painted, as they do not clean off. If they are applied to a surface that needs to be painted, they will prevent the paint from sticking properly.
Most spray lubricants come with a slender straw which can be inserted into the nozzle for precise application of the lubricant. This is important when the oil could cause damage to fine finishes or where oil in the wrong place might attract dirt. While some people get carried away putting oil on things, you are actually much better off pinpointing the oil where it is needed.
Correct lubrication means only applying the oil to bearing surfaces. That means surfaces where there is metal rubbing against metal. Lubricant applied anywhere else does not help protect the machine, but can attract dirt, ultimately causing other maintenance problems. We've compiled this list of the best spray lubricants in 2022