bit of a silly question

apologies if you get to the end of this post and put your face into your palms.

i have been given a shade under 5kg of unflavoured wpc (mp) from a friend who bought it without trying it first and hates it.

i have just bought 5kg of instant oats (mp again) and would like to throw the pair of them together in a breakfast shake.
 
both of them recommend 150-250ml water/milk with 1 scoop whey and 2 scoops oats.

here's the stupid question:
 
if you were to mix the 2, would you use 300-500ml water/milk as suggested for the 2, or use less? 

Add as much water as you like until you get the consistency you prefer, I.e a thicker gloopy milkshake type drink or a runny water easy go down type drink,

Myself I would probably go for
400ml and let the oats absorb the water for around 3/4 minutes to thicken it up

i have a similar breakfast shake. 450ml semi skimmed mild with 2 scoops oats and 2 scoops protein. Since you have unflavoured, you could try mixing in a spoon of coffee and some sweetner (i use splenda) to give it a flavour.