GREASING FROM THE TOP OF THE KINGPIN Pre-2004 (The Argument Against)
by Lorne Goldman 2002 

The unfortunate use of the one-shot oiler began a decdes long (and silly) debate on greasing from the top of the kingpin, using the passage drilled down the shaft. Perhaps the issue with understanding how the original 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 preventing an easy visual analysis. However, even installed, a tape measure can tell you all you need to confirmthe elements. (Or just a glance will do it if you understand where everything is.)

HFS's system for greasing the kingpins was 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 higher than the all-important reservoir.To confirm this, measure down from the top of the kingpin 5 inches and then ask yourself what grease up there can do that could possibly replenish the reservoir. So if you hope to use the oil passage for grease instead of oil, it cannot help in any way unless you drill it further. 

At least, the one-shot oiler inundated the area in oil which had some lubricating consequence for the damper plate (and too often your brake rotors!)

Some 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 front 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 reservoir or whether your brakes had been greased by sad chance? 

Others maintain that the newer bushes, with their spiral grooves cut down in their inboard surfaces, will pick up grease from the top and it will eventually worm it way around to the grease rsservoir. Please step back and think about this conceit for a moment. They are suggesting that you use a hard-to-reach upper grease nipple to force grease down a passage in a long kingpin, squeeze into a sprial groove and have it wind its way down the kingpin into the grease space, which is already filled directly by another grease nipple specific to the reservoir! The saem logic could be used to pour petrol over the entire car in hope it would suck in some place. 

WATCHPOINT: In 2002, the MMC removed the one-shoted oiler system and the oil passage down the kingpin. However, in 2009, they adopted a steering race (bearing system) made popular by eMog. Rather than using one of the systems tasted and used for many years they tried their own. The bearing systems previously in use all use the existing greasing structure to feed the bearing assembly however, this was apprantely not understood by the Factory. Instead, they redesigned the HFS' kingpin once again and drilled a grease passage down the kingpin to a point adjacent their little bearing assembly (steering race)  and have three exit holes in that area that will hopefully fill the assembly. This grease does not fill the aforementioned reservoir. More here.