Oatmeal stout too sweet

Hey everyone, first time poster, long time lurker. I finally have a question that i can't find the answer to searching old threads. Hopefully this is the right place for this thread. If not, please have mercy.
Saturday, 2/19, i brewed my first partial mash using this technique: https://www.homebrewtalk.com/f39/easy-partial-mash-brewing-pics-75231/. This was the recipe i used:
3 lbs light DME
3 lbs american 2-row
1.25 lbs flaked oats
8 oz rye oats
10 oz crystal 80
1 oz black patent
1 packet windsor ale yeast
4 oz lactose

Now i know lactose adds unfermentable sugars, but my beer is pretty damn sweet. The OG was about 1041 before adding lactose. I checked it yesterday and it was 1020, and there were no bubbles in the airlock. I racked it to a secondary carboy and it bubbled rapidly for a few seconds after i replaced the airlock and moved it, but soon stopped. I'm hopeful that it is still fermenting and will dry out a tad.

The author from the thread i got the method, suggests a floating thermometer and i'm sure that is for a reason because when i was using my glass thermometer, i had difficulty measuring a consistent temp.During the mash, it seems as though the bottom of the pot was at about 158 while the middle-top was 156-145. My guess is that my mash temp was off and i've got more unfermentable sugars than originally anticipated. If that's the case would adding some sugar help dry it out in a "good" way? Anybody have any similar experiences and/or advice? thanks,
-Jesse

I think you answered your own question with the 4oz of lactose. I brewed a stout over the holidays, and it was sweet as it was with no lactose. Remember that carbonating will cut back on the sweetness.

One question though, what exactly is "8 oz rye oats"? Rye and oats are two diff. grains.

Cheers.

Corn sugar can help kick start the yeast and dry out the finish. To much and you end up with thin beer..5lb should be helpful.

cool thanks. yeah hopefully the cold+carb=better taste. sry i meant flaked rye. Still considering corn sugar although i definately dont want to ruin a good beer, because although sweet, it has a really nice body. Thanks for the quick replys!

Seems like a stopped fermentation. Ending at 1.020 when starting at 1.041 is only 51% attenuation. You should be shooting for 70% at the least. 4oz. of lactose will only add about two points to your OG on a 5 gallons batch (pretty negligible). I wouldn't add sugar at this point as you run the risk of it not fermenting out as well, and only becoming sweeter. Since you've already racked it off the main yeast cake, I'd build a big fresh starter and pitch it at high krausen to see if you can get it started again.

A little over a week ago, i ended up re-pitching the same yeast(windsor) in a foamy starter. It built up a tiny layer of krausen over night and dissipated through the second night. I checked gravity a couple days ago and it read 1020. It still tastes pretty sweet although it does seem a little dryer. I'm gonna let it go for another week and keg it.

I finally decided to keg this 2+ weeks after re-pitching. The final gravity is the same at 1020 surprisingly. The taste is entirely different though, and it seemed to dry out and mellow quite a bit. It's actually one of the more pleasant brews i've tasted un-carbed and at room temp. I can tell it's low abv by taste and gravity which for me, is a good thing as my tolerance is quite low and that means i can drink more =D. I'm looking forward to this "session stout", and i'll update again after its carbed and chilled.

Leave that stout in the keg for another month and I think you will find that you have a totally different beer and that it isn't as low alcohol as you now think. It takes way more time for a stout to mature than most people think and once it comes together, I think you will find it is no longer as sweet either.

+1 4oz of Lactose...

+1 Let it sit for a bit with the right amount of carbonation and it will mellow out and taste ever better than it already does...

Last bit, if you like it, don't sweat the gravity...

I had a similar problem with an Oatmeal Stout. It finished at 1.020 too and was a little too sweet. 2 weeks later with a tad more carbonation it is a really good beer. The carbonation really helps to cut the sweetness.

I ended up kegging that stout and it was really good after carbed. It was about 2-3% and really drinkable. I finished the 3 gal keg in about a week with some help. I had some left over in the carboy so I bottled it and I'm gonna let it sit for a month and see if it's any different. I brewed another stout very similar to this right after. The changes I made were adding more malts and less extract(only 1 lb) but used the same yeast. I let it sit in primary 3 weeks at about 68 and it seemed all mellowed out. But then we got a heat streak which pushed the temp up to 71 for a day or two. The heat got the yeast started again and it went crazy for a couple days. I finally moved it to secondary after a month and checked gravity(1010) which I was pleased with. I suspect on the previous batch I simply rushed it to the keg without giving the yeast proper fermentation temp and that's why it finished at 1020. I read somewhere that as long as you get the yeast to recomended temp eventually within a reasonable time frame, it will finish properly.

Back to the new batch, it tastes great and is just what I was going for, but after a week in secondary it started to develop a semi-translucent film that trapped c02 bubbles beneath it. I came here of course and I think it's an infection of some kind, although many seem to ignore this type and keg or bottle around it anyways. That's exactly what I did yesterday after tasting it(no sourness, vinegarry, or off flavors detected). If it wasn't an infection, I'm guessing it could be a layer of yeast? But im not sure. Anyways the lesson I took from these two beers is, be patient and don't rush it because it needs time to become what you want it to become. Thanks for all the responses.

Glad the beer worked out. I've generally found windsor ale yeast to have very low attentuation.