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
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.