Gun Oil Friction Test – WD-40

I have read that some people use WD-40 as a gun oil. But is it a good lubricant?

I just started testing gun oils using a simple scientific friction test involving an inclined plane and a metal sled and wanted to test WD-40. So here goes…

WD-40 Friction Test

Here is the setup. A metal sled is placed on the inclined plane. The inclined plane is raised until the sled slides downward. At some angle, gravity will overcome friction and the sled will move/slide. Adding a lubricant should reduce friction and cause the sled to move at a lower angle.

First you test bare metal to see what angle or slope causes the sled to slide. Then you add an oil or lubricant and do the same test again. By comparing the results, you can see if the oil or lubricant reduced or increased the friction. If the sled slides at a lower angle or slope then it reduced friction.

WD-40 Friction Test 2

So I wanted to test WD-40 for myself since┬áI had heard that it is a good lubricant. Bare metal resulted in an average angle or slope of 15 degrees. I then added a generous amount of WD-40 to the incline plane and to the sled and ran the test. It took a much higher slope to get the sled to slide… about 22 degrees, so I wiped the excess WD-40 off with several clean patches and tried again. This time the sled moved at 15.8 degrees. Remember bare metal resulted in 15 degrees. WD-40 resulted in 15.8 degrees. Based on this friction test, WD-40 is NOT a good lubricant.

WD-40 Friction Test 3

WD-40 is advertised as a penetrant, protectant and lubricant. It is a good penetrant and protectant against corrosion BUT lacks in lubrication.

I would NOT use WD-40 to lubricate firearms.