The ornamental design for an oilfillernut, as shown.
FIG. 1 is a side elevational view of an oil filler nut showing my new
design;
FIG. 2 is a top plan view;
FIG. 3 is a bottom plan view; and,
FIG. 4 is a side elevational view, the broken line showing of an engine oil
filler is for illustrative purposes only and forms no part of the claimed
design.