Inexpensive Honing Fluid
You should always use a honing fluid when you use a diamond hone to sharpen a turning tool, the blade of a plane, or even a knife. Without the fluid, the hone is likely to clog with bits of metal and generic gunk, and over time this will render the hone almost useless.
Even though commercially available honing fluid is rather expensive, the expense
should not be a deterrent from using it. The fluid will make your hones, which are
even more expensive, last much longer and they will perform better as well. 
A bit further down, after I tell you a story, I will reveal a product that is readily available and inexpensive that makes an excellent honing fluid. Plus, it smells good!
My Story
Way back about 2008 I purchased two diamond hones. Used them for about five years without fluid because I figured the hones were something like files, and you don’t use fluid with a file. The hones got to where they didn’t work very well.
Naturally I concluded they were worn out and should be replaced. I spent a bunch of money on two new hones and, at the same time, purchased a small bottle of honing fluid.
I was proud of my new hones. So much so, in fact, that I was reluctant to use them. I didn’t want to get them dirty. Instead, I continued to use my old “worn out” hones, but this time I used honing fluid with them.
To my great surprise, they seemed to do a pretty good job. And the more I used them with the fluid, the better they got.
Here’s the punch line: I’m still using them (in 2017)! Rather than being worn out, they were simply loaded up with crud which the honing fluid helped to remove. My two new hones are still in the box, and they are still nice and shiny.
The Inexpensive Honing Fluid
It’s mineral oil. More precisely, … baby oil. Yes,
mineral oil makes a good honing
fluid, and baby oil is simply mineral oil with a fragrance added to it (exact formulations
may vary).
If you don’t like the idea of using baby oil, you can purchase pure mineral oil at almost every grocery store or pharmacy.
Note also that General Finishes Butcher Block Oil 
is mostly mineral oil, just in
case you already have that on hand.