This forum was of great help to me a couple years ago when I built my WorkBee CNC.

I have upgraded my CNC to having HGH15 square Linear Guide Rails.

The instructions say to grease them, but I don't know what type of grease to use.

Also, the grease zerk is very small, and it doesn't have the usual round end to latch onto but is a a six-sided shaft that rounds a bit on the end.  What type of grease connector latches onto that thing? 

Well, I suppose I will try and answer my own question.

I have been told to use "slideway oil."  Of course, that's hard to figure out in itself. I found some in large amounts.

And I was oblivious to these small grease zerks.  It looks like one uses an adaptor that pushes inside the zerk instead of grabbing around the zerk.