12:48 p.m. on August 24, 2006 (EDT)
yeah, right ("expert" HAH!)
Alain asked - "...MSR Dragonfly mult-fuel stove and I am wondering whether to use kerosene or white gas in it."
First comment - While I like MSR stoves and have several of them (including a Dragonfly), the Dragonfly is far from my favorite stove. I would generally have advised you to get an alternative. A friend did a ski traverse of Greenland a few years ago, with a Dragonfly. Midway, the stove totally failed and they couldn't get it to working until after they got home and could completely disassemble and overhaul it. The problem has to do with the needle valve - it needs frequent maintenance and cleaning, and proper operation of the stove, including shutdown (MSR directions don't describe this). They had an XGK along with them, which they used the rest of the trip.
Anyway, to answer your question - use whatever you have available. As Brian noted, you have to switch jets for the light ("white gas") and heavy (kerosene) fuels. I would have to dig the stove out and look, but I believe Brian is right that the kerosene jet is marked with a "K" and the white gas one with a "G".
Either what is loosely called "white gas" or kerosene will work. Technically, in North America, "white gas" is gasoline with no additives (a mix of heptane, octane, and nonane, plus some aromatics - um, that means ring-type hydrocarbons like benzene, um, what is called benzene in the US, not what is called benzene in Germany - confused? well, you should look on the "stove fuels" website). Ed is right that Amoco used to sell something they called "white gas", although it had several additives in it.
For "white gas", what you really want is the "stove fuel" mix that is sold under the names of Coleman Fuel, Blazo, or more generically "stove fuel" (not "Marine Stove Fuel" - that is alcohol for alcohol burner stoves). This is actually mostly naphtha, plus some additives to keep the jet from clogging (you still have to clean the jet.
Problems for "white gas" are (1) as Brian mentioned, you can't get it in a lot of countries, notably 3rd world countries. In Mexico, you have to go to a hardware store and know exactly what you are asking for, for example; (2) it is really flammable. If you spill it, you can get a huge flame. (3) if you spill it or it leaks in your pack, your pack will smell for the next couple of years, and any food it touches is contaminated and poisonous.
In addition to Coleman fuel, with the "G" jet, your Dragonfly will burn autogas (very poisonous fumes, use only in a well-ventilated area, and only in dire emergencies); avgas (same problems as autogas, only emergencies), and similar products. MSR and other stove manufacturers advise against this. Disclaimer - always follow the manufacturers' instructions. Just because others have gotten away with burning random liquids is no reason for you to try it.
Kerosene - Kerosene is available in just about every country of the world. And it is generally cheaper than white gas. It is a bit harder to light, so is safer than white gas. That's why it is used on boats so frequently. But it stinks, both just sitting there and while burning. If you spill it, it will contaminate any food it comes in contact with, just like white gas, but the stench in your pack will last not just a year or so, but years and years, plus leaving a non-removable stain. But at least, it won't explode in a giant ball of flame like white gas, just sit there burning away.
You can also burn autodiesel, jet fuel (JP-4 works really well), and some other heavier liquids (again, MSR and other stove manufacturers say use only kerosene specifically intended for stove use - do as they say). But do not, I repeat, DO NOT try to burn marine diesel, especially 3rd world marine diesel, in your Dragonfly. It will clog it up right now.
Remember, as Clyde Soles said in a stove review in Climbing Magazine some years ago, "treat all stoves as the barely contained explosives that they really are."