I think my right valve cover gasket is no good as I see leaking all down the right side of the engine. Is this the case or is it something else? If so if someone knws the part numbers needed for both gaskets to complete the job I'd appreciate it. (See pictures I took below).

 

Just go to Nissan and tell them you need the valve covers for your year Z. Going to set you back a couple hundred.

 

Should I only get the one that’s leaking replaced or both? Left one is spotless.

 

Might as well do them both while you have it apart. That way you dont have to rip it apart again if the other starts leaking.

Change your plugs while you're in there too.

 

I had the pass side cover replaced by the dealer a couple of months ago; part comes with all plug tube seals, gaskets etc. and I'd recommend just having the Nissan dealer do it; they did mine pretty quickly, saves a lot of time and the price was fair.

 

This is so common they have kit for that. LOL. Do both. Stick with OEM on this replacement.
https://www.z1motorsports.com/cylind...ge-p-7167.html

 

drive side more prone to leak than pass. spark plug #6 seal most likely will give before others. good time to clean it all up. give yourself half day. not a bad job but a lot of things in the way that need to be removed. do spark plugs and take the time to clean out all the oil in ur upper/lower intake plenumn