@raoshahzad
I would like to clarify as
1 - Castrol Magnatec (CM) is bit thicker than ZIC A at cold state, at 40C CM viscosity is 102 while ZIC A 98.46, even at 100C it's 0.1 ahead of ZIC, so ZIC A should have easy start and less consumption (theoretically)
2 - "intelligent molecules" --- every chemical is build up of molecules, which is aggregate/combination of atoms. So the quality of base mineral and synthetic additives describe the QUALITY. You can only experience this difference by using oil as every company claims they have best mineral base or lab additives etc. etc.
3 - Viscosity index is the additive ratio to base mineral to attain certain viscosity at relative temperature. If synthetic additives are not good then they breakdown composition of oil on heating etc. called shear back of oil. Oil doesn't decrease but perform low at this state.
4 - Oil grade like 10W-40 (in SAE system) is multi grade attained by any combination of base and add. but should have standard viscosity range at specific temperatures. API like SM, SL is more qualitative than only grade of SAE.
I have not used CM yet, I think it's good quality oil.
I am currently trying new oil and very happy with performance yet, very soft on engine. it's ENOC 10W-40 from Dubai.
I have used ZIC A twice and was good experience, went 6000+KM in 1990 Khyber.