What iol viscosity to use

In New York or California, you should use the recommended viscosity from the maufacturer. In this case it calls for 5w30. A synthetic is more forgiving, whether it's cold or very hot weather.I use 0w30 year round and for the whole year. I've been in Texas during the summer and I've been in Canada during the winter. My engine in my 4runner doesn't know the difference. The temperature gauge stays the same. It fires up just as easy in the cold as it does in the heat.
Lou