My oat milk is too watery Since shops around here are out of oat milk for past week I started running low on supply. I decided to make one at home. I'm targeting the Oatly full-fat milk.

I blended 1 cup of oats with 4 cups of water for about 30-45 seconds (I used wrong blender so the timing is not accurate as it started to spilling over when blend too quickly) and then put it through cheesecloth. Have I:


Added too much water
Blend too short time (timing was very innacurate)
Not soak the oats first?
Here are the ingredients that the manufacturer’s website gives for Oatly Full Fat:


  Oatmilk (water, oats), low erucic acid rapeseed oil. Contains 2% or less of: dipotassium phosphate, calcium carbonate, tricalcium phosphate, sea salt, dicalcium phosphate, DHA algal oil, sodium ascorbate (antioxidant), tocopherols (antioxidant), riboflavin, vitamin A, vitamin D2, vitamin B12.


I doubt that you can get the full-fat flavour or texture without adding fat. 

The question then becomes how you keep the fat in an emulsion with the water and oats. As the use of heat has been suggested in comments, I would suggest experimenting with making a roux of the oil and fine ground oats and proceed as though making a thin white sauce.