The American company Wahl Clipper Corporation (now simply referred to as Wahl) have been manufacturing hair clippers and related products since 1919. The company is one of the leading names in this field. They know what makes a good hair clipper and how best to maintain them.
Hair clippers and trimmers all work on the same basic principal. Two layers of blades (or 'teeth') slide from side-to-side, in a cutting motion. When in use, the stainless steel teeth work in a very quick motion; the two levels of metal gliding over each other. This of course, causes friction. The friction, over time, can lead to the slow blunting and dulling of the teeth, meaning repeated work when trimming hair until finally the clipper or trimmer is of no use anymore.
In order to prevent this blade damaging friction, a few small drops or a thin line of oil to the sliding blades will lubricate between the layers of stainless steel, which in turn will dramatically reduce the levels of friction. Doing this before every use (or every other use) will drastically prolong the life of your clipper or trimmer blades.
Wahl Clipper Oil is specifically designed and manufactured to be the best consistency and texture for the use with clippers and trimmers. The oil has a translucent faintly yellow colour, which does not stain or dye hair, skin or clothing at all.
I have a few clippers and trimmers to maintain my short haircut and (hopefully) neat beard. In order to get the best possible life and performance from these appliances, I have regularly used this Wahl oil on their blades - which I have been doing for a number of years now. The 4 fl oz bottle provides enough oil to last for years and years for general home use. Only a small drop is required in 3-4 places on the blades, so the amount being used is really of such a small quantity. Honestly, even if you use the oil before every use, you'll still find that the bottle lasts for years.
For the cost of one bottle of the Wahl clipper oil, as well as the regular hassle of having to spend 10 - 15 seconds to lubricate the blades before each use, I still stand by the oil being a massive cost saver as well as a huge time saver. Without using oil, you would need to either replace the blades (so have to find somewhere to get the replacement parts) or more likely, have to replace the whole clipper/trimmer. Expensive and time consuming. Using oil on the blades is a no brainer really! And this Wahl oil has worked perfectly for me over the years, so I'd recommend it to anyone.