Originally Posted by andrewdoherty

What Sean said is correct about new o-rings. I personally don't replace the o-rings. Once the black washer has been pressed all the way down to the shoulder I place the o-ring on. With the fingernail on my ring finger holding one side of the o ring down, I use the tip of my thumb on the same hand to press in and down which allows the oil to escape from underneath the o-ring. I might take a couple tries, but you'll know you have enough oil out when the o-ring is flush like redbull said. When you do it like this you don't have to worry about how much oil to put in. Just fill it and everything not needed will spill out.