ISO (International Standards Organization) does not have oil quality standards. They are, however involved in viscosities and almost everything we touch theses days.
The viscosities for industrial oils (gears, hydraulics, compressors, etc. used to vary all over the place: you could see equipment asking for VG (Viscosity Grade) 37, 42, 78, etc. Also you saw companies specifying the oil viscosity at 50 C or 70 C. ISO came along and after working with the industry came out with suggested standards: That the Viscosity be specified at 40 C or 100 C, and that it be in increments in a scale that starts thin and adds 50% visc to each succeeding number: ISO 32, 46, 68, 100, 150, etc. each is 50% more viscous. For the most part this works and makes it easier to cross reference and supply, although there is still some old equipment that requires other grades.(I have a customer who needs a VG 78 turbine oil - 68 is too thin and 100 too thick). Bob has a chart posted here that shows the relationship to SAE viscosity grades.
ISO also came up with the little symbols on the dash board of cars that standardize the little snowflake as the button for A/C, the icon's on the dash, etc. They are working on standardization of sizes of clothes and shoes so all "M" shirts would be the same size, no matter what brand or country of origen. They are standardizing everything that they can.
The ISO 9000 family of numbers is very misunderstood. ISO 9000 or 9002 does not guarantee quality. ISO 9002 is not better than 9001, the company with ISO 9002 basically is just not involved in development, only production, sales, etc. The ISO 9000 family guarantees that the plant has controls in place that should guarantee that product "X" will be produced the same day-in and day-out, no matter who is working. It puts no standards on the actual product you produce. ISO does not inspect or certify, certification is done by third parties. It's implementation and inspection varies more from country to country than they would like to admit. Many of the ISO 9002 certificates in Latin American would be revoked if a US inspector checked.