How much chocolate extract for a 5 gal. batch?

Hey all,
I just made a Chocolate Oatmeal Stout with 1 oz cocoa powder added at flameout.  Not too much Choc. flavor at all, if any.
I was planning on adding choc. extract at bottling time for more flavor.  Any suggestions on how much to use from your experiences?
Thanks

The best thing to do is determine it empirically.  Pour 4 2 oz. samples of the beer and add a different, measured amount to each.  Taste and determine which you like best, then scale the amount up to your batch size.

A 5 gal batch of robust porter came out very nice with 6 oz. unsweetened bakers cocoa added at the 15 min remaining mark, and
approx 3/4 cup of creme de cocoa (this was added by Denny’s method of taste at increments) after 5 days in the fermenter.

I hopped conservatively and the cocoa actually provided a nice amount of bitterness. The chocolate is just detectable in the
aroma, a nice tease on the pallet and a pleasant lingering chocolate in the finish. I like my beers to taste true to their base styles
and the additional ingredients to be a pleasant surprise to your taste buds.  This amount produced what I was looking for.

I tend to use 8 oz of unsweetened cocoa powder at flameout for chocolate beers.  Also you want to try and take a lot of that chocolate sludge with you on its way to the carboy.  The longer you leave it on the chocolate the more flavor its going to get from it(of course you dont want to leave it on so long to get yeast autolysis).

Cocoa nibs in the secondary is also good for chocolate flavor.

Chocolate syrup to me tastes awful

I’ve never tried chocolate extract, Denny’s method is best.  You also want to consider how long you want to age the beer.  Age tends to mute flavorings, so if you’re doing something like an Imperial Stout where youre aging for a long period of time you may want to add a bit more than you would think you’d need.

I added 2 oz. extract at bottling, forgot to mix after adding the beer.  The first few bottles had a strong choc. flavor, then realized I need to stir it up!  After stirring, it has a nice subtle choc. flavor that complements the choc. malt and other roasted grains.
I might kick it up a notch next time, will see how this ages and if it loses any flavoring over time.
Thanks All!