I suppose the manual says it all 5w30 and 10w30 are primary choice and u can use 15w40 and 20w50 oils too important things is SN grade superseded other grades. these grades qualify that a certain oil has passed certain test standards regarding its lubricating, cleaning, cooling and stability.
The API SN category is an improvement over the API SM category in the following areas:
High temperature deposit protection for pistons
Better sludge control
Better seal compatibility
This means that API SN compares to API SM like this:
if you look at the diagram it shows that SN has better deposits cleaning capability so it will keep engine cleaner. In short if u use 20w50 oil u can but a 5w30 or 10w30 etc oil is better cause it will have a better Grade.
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