Greetings Slowryde, & welcome to the caffeine fuelled world of CoffeeSnobs ;)
I gather from the time of your post, yet saying good afternoon, that youre not Oz based. That may explain why Ive never heard of the brands of soy that youre using.
However, from my experience steaming soy (regardless of brand), it reaches boiling temp a lot quicker than standard milk, & it tends to foam (ie separate in molecular structure) very quickly if the wand is left hovering just below the surface when steaming.
Admittedly Im not familiar with the Oscar, but can you regulate the intensity of steam output via a knob, or is it an on/off lever with a pre-programmed level of steam? :-?
Either way, with soy Id suggest immersing the wand deeper into the milk, minimise the ch-ch-ch sound, get the swirling whirlpool happening by angling the jug, & cut the steaming short because it heats very quickly. That way youll minimise the bubbles, and separated foamy marshmallow on top. Aim for even texturing.
And ... if the above suggestions dont work, well, ditch the soy & drink it pure & black - the way espresso should be appreciated. ;D
IMHO, soy has its place in this world, but not mixed with coffee ::)