I have some lager yeast and a dry stout kit. Would it be a bad idea to use the lager yeast or should I stick w/ the ale yeast?
If you ferment at the typical ale temps, the lager yeast probably won’t fully attenuate and you’ll get a stuck or incomplete fermentation. If you chill it to lager temps it might work. The yeast profile and the malt charactistics of the stout might actually make an interesting combo; perhaps akin to a Rauch.
Unless it’s a California Lager yeast, you need fermenting temps between 30-50 degrees Fahrenheit for a lager yeast to be really happy, so unless your furnace is on the fritz or you’ve got a spare fridge, go with an ale yeast, but you already knew that because I type slowly.
My local store’s webpage has a dry stout that uses an irish ale yeast (here):
It will be at lager temps
If I’m not mistaken, making a stout kit with lager yeast is pretty close to a Baltic Porter.
Check out 12C on the BJCP judging guidelines.