No offence but should I say Aaaaaawwwww 
Someone explained it better than me:
The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100°C. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number, the thinner the oil: a 30 oil is thinner than a 40 oil at 100°C etc. Your handbook will specify whether a 30, 40 or 50 etc is required.
This means that "5W-30" does not mean it is a temperature range. No. It is a multi grade oil meaning it flows differently at different temperature. As someone wrote:
Most oils on the shelves today are "Multigrades", which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)
Multigrades were first developed some 50 years ago to avoid the old routine of using a thinner oil in winter and a thicker oil in summer.
In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature. The lower the "W" number the better the oil's cold temperature/cold start performance.
Use only the oil designated by the engineers who designed the car's engine, 5W-30 in your case, I use 5W-30 Shell HX-7 Blue Pack throughout the year.
And about ZIC oil. A+ I beleive is 5W-40 and too thin for Mehran,
And who told you that 0W-30 is temperature range?. Serious question.
