If the oil is leaking from the BASE of the oil sender, where it threads into the engine block, you can try to tighten it a bit.......by installing a wrench or socket on the LARGE metal end of the sender. Don't tighten it too much though.....it is a smaller end that threads into the block.
If the oil is leaking out of the small end, or around the joint between the large metal end and the plastic, you need to purchase a new oil sending unit and install it with teflon tape on the threads or a oil proof thread sealer, prior to threading it into the engine block.
