we are trekking in the High Andes culminating with an attempt at Mercedario 6700m perhaps highest camp 6000m coldest maybe -40F (or C). Would a meths stove big enough to melt snow work up there? most of the time we are lower so the weight saving is desirable. Any tricks to make it work? I assume the lighter and fuel bottle would be good warmed in clothing before attempting to light it.

I haven't used a meths stove at that altitude and haven't seen any discussion of it in the past - maybe check Trangia's website as they do have some technical info. The cold alone shouldn't be an issue because Trangia's were designed for use by the Swedish military. Trangia do have a pre-heater cup/tray: since I've seen Trangia's used below zero in Australia I've always thought the pre-heater was unnecessary, but the intention may have been for winter use in northern Europe, i.e., below -20C. Perhaps Roger can offer an opinion re the altitude question? The issue would be the effect of altitude on the boiling point/combusiont/burning efficiency etc.

But even if you decide to not go with meths, I've heard that the canister adapter for Trangia's is excellent in cold/high areas.

Re weight saving, I've seen arguments in the past that once you tot up the amount of fuel needed for a meths stove, past a certain number of days without resupply you're better off with a fuel with more inherent energy.

Hi Derek

Yes, a metho stove would work at that altitude.
But you would soon regret the decision! It would be desperately slow and weak. As for melting snow ... I think you would be getting a bit dehydrated.

You can guess my preference.

Cheers

I think an alcohol stove would function, but its effectiveness would be minimal.

You will probably fly to Santiago, then over to Mendoza before you get started on land. Mendoza is the place to get permits and purchase your fuel. It would be easy to find butane blend canisters there, but liquid fuel is much easier and probably more practical high on the mountain. That is especially true if you get a multifuel liquid stove, because the quality and nature of the liquid fuels that you buy there are not perfectly controlled.

I remember that we were directed to a hardware store near the permit office, and we went there with each expedition member carrying two empty liter-size Sigg bottles. The hardware store man said that he had "gasolina blanca" for US$1 per liter. So, we handed over our bottles, and he brought them back full from the bulk drum in the back room. We paid and left. After we had walked a mile back toward the hotel, one of the guys asked how we knew what we really had in the bottles. We did a test burn that evening, and it burned hotter than the white gas we knew from home. Virtually everybody on Aconcagua was using white gas, and I can't imagine that it would be that much different on Mercedario.

--B.G.--

+1 to --B.G.'s-- post. General consensus limit of alcohol stoves is around 10,000 feet. Butane with a self made pre heater can go higher. Most give up and use white gas or gasoline and suspend them from their main tent pole or put said stove on a shovel in the snow instead of carrying a base plate.

Cheers

Yes, among the liquid fuels, in some countries white gas is more easily available, and it seems to be clean-burning. In some countries, you may find kerosene first, and it has a higher energy content. In other countries, automobile gasoline is more common, but you have to watch out whether you are getting unleaded or otherwise.

--B.G.--