5W-20 or 0W-30 , viscosity grades are best for any harsh weather, Temperature, Road, environment and load conditions, secondly a raw person usually thinks that 5W-20 means the oil which is suitable only in that place where ambient temp. is between 5 to 20 centigrade and same with 0W-30 but their is not such in reality as 5W-20 or 0W-30 are the viscosity grades of oils. To understand it first of all let it be very clear that basically all oils have two major gradings 1. Performance grading 2. Viscosity grading , and in more easier way think One person (A) has his weight 100 kg and he can lift only 50 km wt and another person (B) who has his wt 55 Kg and he can lift 80 Km wt , so persons own wt can be called viscosity and its wt lifting capability is its performance like wise oils have their viscosity grading and performance grading
Performance grading is represented in API (American Petroleum Institute) which shows the performance limit of any oil product that how an oil can perform in engine and the latest performance grading of Gasoline Engine oil is API SN, and for Diesel the latest Diesel Engine oil Grading is API CJ-4, and in Pakistan CI-4
for Viscosity grading it is represented in SAE Grading like 5W-20, 0W-30 , 10W-40 ect and they only shows how an oil is viscus or lighter in their physical state. Additionally every newer engine like 0 meter to 50-60 K needs lighter viscosity oil and all older engines required viscus oil as wear and tear took place between engine ring and cylinder walls,
In the last API has categorized all the world into 3 Temp. zone as shown
http://www.api.org/certifications/engineoil/categories/upload/MOTOR_OIL_GUIDE_2010_120210.pdf
so 5W-20 and 0W-30 viscosity graded oils are best in Paki Envo.
Thanks