Your in New Jersey, temps are cold, yes, .... use a 10w 40 weight oil.
The easiest way to explain this is temperature change. If you have one weight oil, it's meant to be used in pretty much one type of season, or temperature. If you use a variable weight oil, it will protect the motor through the different temperature changes of the year
The weight determines the viscosity. When oil is heated, it thins. If you use one weight oil, your limiting the oil to one temperature range, one viscosity.
You should always use your owners manual requirements for oiling/lubrication. This is a very important part of maintenance that will protect and give you the most life of your engine possible. Using inferior products or not what is recommended, wont' be noticed right then, it will be noticed in the life span of the motor.......:cheers: