the finer the oatmeal the better it will suspend of course, and the only thing I do different that what you decribed, is I dont stir so much, after I add oatmeal and fo or whatever else, I let it sit, until a skin forms on top then stir it well, sometime I will let it skin twice and stir before pouring.. also if yu just have too much oatmeal per lb, some of it is just gonna settle, if this doesnt work for you I would try reducing the amount or buy a supsending Mp base, or buy some cosmetic grade silica and make your own.