Bottling Oatmeal Stout

Yes, priming is needed for any bottled beer, unless you plan to force carbonate in a keg and bottle from there. There are bunches of bottle carbonating calculators out there. Here's one...

http://hbd.org/cgi-bin/recipator/recipator/carbonation.html

It will tell you how much sugar you need to use to reach your desired carbonation level.
For an oatmeal stout, I'd recommend keeping the carbonation low-ish, maybe about 2.0 volumes. That will help the chocolate/roasty flavors come through, especially as the beers warms up.

Edit: And read www.howtobrew.com

 

Once fermentation has completed then the yeast have no more edible sugars to eat, thus no more CO2 will be given off from your beer. If you want CO2 in the bottle, then you have to add more sugar to get your bottle carbonation.

P.S. Welcome to the BA site. Stick around as long as you'd like, and enjoy your time while here.

 

I would use 5 oz per five gallons.

 

This is not critical. It will take very little water to dissolve 3.2 oz of sugar, probably as little as a couple of ounces. Remember, you are boiling it (to kill any sugar-bacteria) . . . it's pretty impressive how it dissolves. Let it cool to near the beer temp and mix thoroughly (stir gently to minimize oxidation), consider a few extra stirs as you bottle to keep the sugar homogeneous. Oh yeah, the 3.2 oz of sugar is by weight . . . many of us use a simple postal scale. Usually the water will be measured in ounces by volume. Ahhh . . . don't you love Imperial units.

Final suggestion is to search this forum for "how long to bottle carb", "what temp to bottle carb", and "my beer ain't carb'ed yet" threads . . . will prepare you for the next step.

 

I don't think the calculator mentions any ratios to water, but it looks like you and @PortLargo got it sorted, so carry on!
BTW, you don't have to use corn sugar. If you already have it, great. But table sugar (sucrose) is cheaper and just as good. In fact, it takes slightly less table sugar than it does corn sugar to get the same amount of carbonation. Just be sure to choose the type of sugar you'll be using in the calculator's "priming ingredient" section.

 

As mentioned above, the amount of water to use for dissolving your sugar is not critical, but take a look at your finished volume of beer to help you decide. I have used a quart of water at times when I discovered that I was a quart short on my beer volume due to boil off or trub loss. If you want to be accurate to your recipe, and if you are short on your beer's liquid volume, then use the sugar-water solution as top-off. Actually, the sugar in a larger volume of water makes a thinner solution, thus it mixes easier into your beer, so that's a plus. But as suggested above, it's a good idea to stir gently when adding the sugar to the bottling bucket (many homebrewers add the sugar solution first to the bottom of the bucket so that the siphoned beer will mix into the beer as it flows into the bucket and over the sugar solution. If it's a thick sugar syrup, it may not dissolve so well, so gentle stirring is good insurance. (Stir without making bubbles.) I also advocate gently stirring the liquid several times during the bottling process too so that the sugar stays suspended in the solution. (It's heavier than the beer and wants to drop out of solution.)

 

I tend to measure an even cup into the pot I'm gonna boil into, throw that on the scale, tare it out, and then pour the sugar in to reach the weight desired. VIOLA! Just the amount of priming sugar I was looking for, ready to be dissolved and sanitized.