Do not go below 5W30. I personally do not recommend in the long run using any thing below this viscosity grade oil.
0W20 is recommended in the owners manual for best for best fuel consumption but for weather in Japan. Considering average weather being hotter in Pakistan than Japan, the oil Vicosity (minimum) for the engine has to be RE-ESTABLISHED; yes RE-ESTABLISHED , which definitely will be higher than 0W20. Now, the next one step is 0W30 or 5W30. The second number is important here, which represents the higher operating tempertaure side of oil for the engine.
Note: During intake stroke, or suction stroke, the air entering the engine is very hot as compared to what we get in Japan, hence a higher viscosity grade than 0W20 shall be safe for the life of engine in the long run.
In hotter climates, It is rule of thumb in engine oils to have viscosity higher than 10 mm2/sec at 100 degree Celsius temperature so that layer of oil is maintained between the surfaces in contact with each other in the engine and this is the case with 0W30 and 5W30 oils. With 0W20, it’s generally lower than 10 mm2/sec.
5W30 is also the best option to use for year round temperatures in Pakistan.
SN grade is recommended as it’s the top grade established in 2010. It’s has low content of zinc (less than 1000 ppm) which is responsible for blocking of catalytic converter.
Fully synthetic oil is recommended as you can increase the oil change interval to 10,000 KM. If you cannot find fully synthetic oil, then the oil change interval goes down to 5000 KM.
