The ornamental design for a radiatorgrill for an automobile, as shown and described.
FIG. 1 is a front elevational view of a front bumper for an automobile showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side perspective view thereof;
FIG. 6 is a top, front and right side perspective view thereof; and,
FIG. 7 is a bottom, rear and left side perspective view thereof.
The broken line showing of the radiator grill is for purpose of illustrating environmental structure and forms no part of the claimed design. The rear view of the radiator grill forms no part of the claimed design.