How quickly does a change in gravity affect its surrounding?

[Fowler]

If the gravity of an object changes ( due to it's energy changing into mass ) how quickly does a second object get affected by this change in gravity? Is it instantaneous?
If so then could information be transported faster than the speed of light using changes in gravity?

Of course I can't see how this would be possible, but can somebody please explain where I've went wrong. Thanks.

 

[axmls]

The rate at which a gravitational force "travels" is the speed of light.

 

[DaveC426913]

Yup. Gravitational change propagates at c.