I've always used some organic for oak.

[Mike Corazzi]

But I am wondering if it would be happier in all pumice?
I've used pumice to rescue some trees but the oak has always had some organic.
Thinking being that where they grow in fields would be a bit of everything.

Although there is no green in the buds this year (so far) it will soon be repot time.

 

[penumbra]

I just read a book, The Nature of Oaks. It is a great read, especially if you are into entomology.
I am going to start composting oak leaves for soil mix.

 

[nuttiest]

Oaks are great at modifying their own soil.

 

[Potawatomi13]

Personally use about 50% organic+50% Pumice to aid H2O retention in hot weather.