Question about oil heat?

We have oil heat which powers a boiler generating steam. There are radiators in every room of the house. My question is, does shutting off the valve of a radiator in a room we're not using save oil and hence money? Will shutting off valves actually decrease the amount of steam produced which in turn means less oil burned? Or is the same amount of steam still being produced but just re-routed? Thank you everyone for your input.