> Really? White gas won't light at -30?
> I have run coleman double-burner stoves at -40, but it was like 20 years ago and I can't remember if they were hard to light.
Well, let's start by remembering that liquids don't burn: only gas burns. So whatever the fuel you are using, it has to be vaporised: it has to reach boiling point. A liquid below its boiling point only gives off a little vapour, like warm water evaporating compared to water boiling.
A lot of the discussion in the Forum has been about propane (C3H8), which boils at -42 C, and butane (C4H10), which boils at -0.5 C . White gas uses much heavier hydrocarbon molecules - in the C5 - C10 range I think, and has a correspondingly higher boiling point. There is not going to be much vapour coming off it at -40 C! So finding enough vapour to light could be difficult. Equally, alcohol at -40 C has not a lot of vapour either.
However, if you can warm up a little bit of it with a match say, then you have a chance to get some feedback going and the stove may start to prime. Little different from ordinary priming really. Incidentally, priming kero is even more difficult for the same reasons.
Why a match? Because a match head contains its own oxidiser and can be made to light under quite cold conditions. A butane lighter probably would not, unless it had been living inside your clothing (which is not a bad idea, btw!).
The comments about pentane, hexane and octane are entirely appropriate, and I agree and have done the same thing myself. However, they are not easy fuels to obtain in ordinary shops.
What about auto gas? Well, winter gas at least usually contains some butane. This should be obvious if you think about how easy it is for auto gas to 'flash'. Dangerous stuff. That is why we have Shellite and Coleman Fuel: they are similar to auto gas but without the noxious additives and without the butane and (iso)pentane components which can flash easily. The manufacturers leave out the really volatile components to make them safer.