I just took over ownerships of an '05 350z yesterday, and I noticed that while I'm driving the oil pressure is staying at 60(around 2k rpms) and if I shift to fast it jumps to nearly 90, but if I shift slowly it stays at 60. I changed the oil today, but the problem still persists. And also, the reservoir for the coolant is filled extremely low, almost barely at minimum, the previous owner has the bolt holding the reservoir hand tightened because he told me sometimes it will start steaming from the reservoir and he has to pull over and empty the tank and refill it. I'm thinking(and hoping) its just a water pump issue, or an ordeal with one of the hoses. But if that is not the case would a new radiator(and hoses/water pump) fix the problem you think?
Sorry if this is answered or dealt with in another thread, I tried looking did could not find any other instances of this specific problem on the forums.

Thank you for any help!

 

are you staying on the throttle for your "fast shifts" if so , it explains the needle jump, but honestly, if its maintaining proper pressure, then I wouldnt worry about that.

As for the "leak" it sounds like the car is overheating, and its coming out the overflow tank. That tank doesnt have to be full, as the coolant is in the radiator, and should only return to that tank when the pressure is too high. Do a cooling system flush (easy, anyone can do it, stuff can be bought at walmart) then, Id data log your temps, you can download an app for your phone, and buy a wireless adapter off amazon or ebay. I bought my adapter for 17 bucks, apps are free, with some more advanced features limited to the paid versions.


You could just try and keep an eye on the temp gauge, but thats not a very reliable way to see whats going on.