WARNING: This page is about a different car, the 2005 Infiniti FX35. However, it is still accessible from the selected car via links, so may be relevant.
Align cutout on oil cooler with protrusion on oil pan (upper) side, and tighten connector bolt.
Fig 1: Aligning Cutout On Oil Cooler With Protrusion On Oil Pan Side (2WD Model)