Well I feel that there is no difference in 0/20 viscose oil and 5/20. Why?
Because according to SAE Viscosity standards J300,
0W has 3.8cst at 100degree Centrigrades
And
5W also has 3.8cst at 100degree Centrigrades
Hence it will be OK to say that for ZIC A+ users (5/20), this 0/20 oil will perform absolutely well too.