Redex has proven results dont include it with all those phoney performance additives. When building engines I used to soak my valves in redex and the old carbon just wipes off it
However as said "some" premium fuels contain redex type additives Shell Nitro for example
In the OP's case its really not required though, any detrimental effects of running low on fuel wont be fixed by adding Redex , it wont do any harm though