There's a pretty big quanta of misinformation regarding "oilstones" in particular and Arkansas stones in general. But the consensus that waterstones are faster is true.
I'm puttin "oilstones" in quotes, because they don't require oil. The stones work better and faster if you sharpen with water or dry. The stones only work well if they're fairly clean. They may be cleaned effectively in the dishwasher, and also by boiling with some dishwasher detergent.
Coarse, as it applies to stone grits, is spelled with an "a" and not with a "u."
Good quality Arkansas stones are available. However, just because stones from different quarries have the same names, doesn't mean they're equal. In fact, they aren't.
Norton translucents are excellent. Hall's surgical blacks are just as good, but significantly less expensive. I'm not a big fan of Norton, Hall's or Dan's soft Arkansas, but prefer Norton by a slight margin.
If you're a serious sharpener, you'll bypass the nominal "hard" stone because it's too slow for sharpening and not fine enough to polish. A good final stone after a fine India, for an ordinary kitchen -- but few ordinary home cooks still sharpen on stones. Take it for what it's worth.
Going back to the translucent and surgical black: They both polish to the equivalent of around a Shapton Pro 5K, and will polish fairly hard steels -- if a little slowly. In exchange for the lack of speed, they require little or no maintenance, remain reference flat for years, and last virtually forever.
I'm ambivalent about soft Arks (currently using a Hall's). Roughly the equivalent of a 1000k waterstone, they're much slower. Because of the speed, I use mine to refine and chase the wire I started on a faster stone (fine India), and as a time-saving intermediate step to the surgical black. I've used a soft Ark successfully on an edge as hard as a Hiromoto AS, but it took a lot of time, and time means it takes very consistent angle holding as well. I'd draw the useful line at right around 60 Rockwell "C" hardness.
Hard to beat the Norton fine India -- as long as it's kept very clean. The rough equivalent of a 600 to 700 grit waterstone, they're a little slower but far more forgiving to inconsistent (freehand) angles, and leave fewer scratches up the knife. Nice consistent scratch pattern. They'll sharpen anything, no matter how hard, with patience.
A Norton coarse India is probably the most forgiving of very coarse stones -- oil or water. I prefer it to Crystolon even though it's slightly slower. BTW India is aluminum oxide, and Crystolon is silicon carbide.
To my mind the trade off in maintenance requirements between high quality oil stones and water stones, especially in the coarser grits, makes the oil stones a reasonable alternative for all but the hardest alloys. This is also, but perhaps slightly less true for the polishing Arkansas grits. If there's a really good soft Arkansas on the market, I've yet to find it.
You can move swarf off the stone more quickly if you sharpen with water, but you'll get a faster stone that leaves a higher polish if you sharpen dry. If you sharpen a lot of knives in a session, use water. Oil makes your stones scratchy, slow and harder than heck to clean.
Disclosure: My oilstone sharpening set consists of fine and coarse India, soft and surgical black (Hall's) Arkansas. My kitchen knife set consists almost entirely of antique (or very old) French carbon Sabatier. My pocket, tool-box, and camping knives are a motley bunch including some fairly hard steels. The knives and stones work very well together. I'll be purchasing another waterstone set one of these days. Either before or at the same time I buy a few Japanese kitchen knives.
Hope this cleared a few things up,
BDL
