Mystery bolt on the firewall side leaking oil
 

This is on a 1998 Maxima (actually an Infiniti I-30) V-6, 3 Ltr, AT, firewall SIDE of the motor, accessible with the passenger tire removed. From underneath, it is directly IN-LINE with the oil pressure switch and it is NOT on the timing chain cover (FRONT). The picture is of the bolt hole, accessible to the left of the crankshaft pulley. You can see the alternator belt and if you follow the oil filter due north and above the bracket that holds some lower cabling , it visible. It's 12 mm, and has a copper crush washer. I used some of that indicator dye with a UV light and honest-to-God...there was the leak. NAPA guy was so frustrated not finding a price on a copper crush washer that he just said, "here, remember us". (I will). Anyway, Nissan dealer had no idea why the bolt was there and mounted to nothing. Parts guy and mechanic offered a "well, could be that motor may have had other applications and we see these on motors. They could go into an oil jacket (which mine did--leaked about 4 ounces out) or a water jacket". Question. Anyone have a clue what the torque specs are or just 'tighten till snug' advice. Use any sealant (after all, it's the source of the leak). Any suggestions are, of course, appreciated.

Unless we were to crawl under our car to take a look, there is not enough information to help you.

It looks like the bolt attaches something to the engine block. Which object is it bolted in to.

please take additional photos , zoomed out so that we can tell where that bolt is.

I've seen bolts appear to drip oil from a leak which is actually higher up on the engine, or up wind.

Is it bolted into the valve cover by chance?

If so, you need to replace the valve cover gasket.

Which will require removing the upper intake manifold.

You should do a search regarding which additional things can be done while the upper intake manifold is off. Or you will be removing it again, probably some time soon.

If it's the bolt I'm thinking about, it's actually on the rear timing case. It's an oil passage. Part of it leads to the main chain tensioner.https://cimg1.ibsrv.net/gimg/maxima....8a6147af88.jpg
https://cimg3.ibsrv.net/gimg/maxima....5ba48533c8.jpg