The ornamental design for a multipurpose oval basket, as shown and described.
FIG. 1 is a plan view illustration of the multipurpose oval basket of the ornamental design;
FIG. 2 is a bottom view illustration of the multipurpose oval basket of the ornamental design;
FIG. 3 is a side elevational view illustration of the multipurpose oval basket of the ornamental design, the opposite side elevational view thereof being identical therewith; and,
FIG. 4 is a front elevational view illustration of the multipurpose oval basket of the ornamental design, the rear elevational view thereof being identical therewith.