Perhaps the issue with understanding how the one-shot oiler CANNOT function as a greasing system arises out of the fact that most of us never see or study the kingpins carefully before they are installed, and then, after they are installed they are covered by their main springs and their dust covers. However, even installed, a tape measure can tell you all you need to confirm what I am saying here. (Even just a glance will do it if you understand where everything is.

HFS's system for greasing the kingpins is by filling the grease reservoir formed in the stub axle tube (the passage the kingpin is installed) in the space between the upper and lower bushes. The lower grease nipple is placed exactly at the reservoir and allows us to fill it with grease. When suspension goes up and down, the resevoir of grease travels up and down the kingpin.. greasing it and the bushes continually.

Now look at the diagram on the right. As you can see, the one shot oiler passage exits the kingpin  above the stub axle and much higher than the all-important resevoir.To confirm this measure down from the top of the kingpin 5 inches and then ask yourself what grease up there is doing that could possibly replenish the resevoir are get near the bushes (especially the all important lower bush) and the kingpin. If you use the oil passage for grease instead of oil, it cannot help in any way with a stock one-shot oiler kingpin.
 

There is more confirmation by examining the image on the right. This photo shows what is happening with the remote greaser or any system using the one-shot oiler passage for grease. The grease simply exits, forms gobs and slithers down the side of the kingpin until gets to the stub axle and falls to the ground. There is NO OTHER EFFECT.

At least, the one-shot oiler system dowsed the area in oil which had some lubricating consequence for the damper plate.

Some say say that a remote system extends the life of the front end. It cannot. Additionally, if it is imagined it is a replacement for filling the stub axle grease reservoir, you will shorten the frotn end life for lack of grease. HOWEVER, there is some logic in modifying the kingpins and extending the one-shot oiler passage all the way to a point where it can reach the bushes and the grease reservoir. But then, how would you know whether you had filled or over-filled the resevoir or whether your brakes had been greased by sad chance?