I had a big oil leak about a month ago. I was hoping it was coming from my Oil Pressure switch, but it wasn't. The leak was coming from where the main oil pan contacts the block, directly above the oil pressure switch. I had to take the car in to get fixed at a cost of about $1,000 (can$). Apparently the oil pan developed a hairline fracture, so it had to be replaced. They had to order the pan directly from Japan, said one wasn't available in Canada?? Anyways, got the car back, a few days later, it started leaking again, just as bad. The car is back in the Nissan Dealership, and they don't know why it is leaking, apparently from the same place. They suggested it may even be leaking from where the timing cover meets the block/oilpan. Anybody else have a leaking problem similar to mine, with some tips or suggestions on what the problem could be? They replaced both of the crankshaft gaskets, as required, and used silicone on the rest of the pan.
I have 2 1998 Maxima's, one a 5 speed, other an auto, the auto is the one with the problems. Would hate to sell it, but I have my eyes on a 2006 G35x.

 

Yes, see this thread:

http://forums.maxima.org/showthread.php?t=453297

I have yet to figure out what is causing the leak. I thought at first it was the right rocker cover gasket or the oil pan gasket, but replacing them had no impact. When the engine runs I can watch oil slowly seep out of this hole. It's hard to see or get to; you may need to remove the P/S pump and the bracket that holds the oil pressure sensor/crankshaft sensor wire harness.