  The effect of modifying General Relativity with the addition of some higher
dimensional operators, generalizations of the Goroff-Sagnotti operator, is
discussed. We determine in particular, the general solution of the classical
equations of motion, assuming it to be spherically symmetric, not necessarily
static. Even in the non-spherically symmetric case, we present a necessary
condition for an algebraically generic spacetime to solve the corresponding
equations of motion. Some examples of an application of said condition are
explicitly worked out.
