Ch Sahib.
New breed of cars like the Hybrids, & Normal cars now use thin oil. The reason is that due to advancement in manufacturing the tolerance in engines have gone down, so there is very little gaps for oil to pass therefore you need thin oil.
As regards to the "Oil Film" or oil coating that is dependent upon other additives present in oil.
Locally produced Honda Civic Turbo uses 0w-20 oil.
Hybrids need 0w-20 whatever the weather conditions may be.