i have a 03 Z and i've noticed that my oil pressure gauge doesn't match my RPM revs. it doesn't go above 60 even when i floor it. performance seems fine and no oil leaks under the car so the only thing i could think of is a leaky valve cover gasket that needs to be replaced. When i changed my plugs one cylinder the back left( looking from the front of the car i think cylinder 6) had some oil on the plug. my main concern is that my car is burning oil. my tail pipes don't really look blackened other than whats to be expected from any car. This troubles me and i'm hoping that its just a gauge, but i don't know how to check it without replacing, and i hope that its not a compression issue i live in houston and have no idea where to take my car as i'm a broke college student and can't afford getting raped from going to mechanic to mechanic. i usually do all the work myself if possible.

list of mods (which i don't think would be the issue but jic)
5/16 plenum spacer
test pipes
nismo cat back
osiris tune (i daily drive this car on tune set-up)
car has always used mobil 1 full synthetic and changed every 4k miles

any and all feedback would be greatly appreciated. its late and i'll check my oil in the morning, but as i stated i don't really smell burning oil and there is no leak except as stated above from the valve cover gaskets..which hasn't hindered performance to my knowledge as i spanked a g37 on my way home from class

 

so i changed my oil to 10w30 today and the gauge is working fine again. no problems. this only leads me to believe that i may be burning oil? if the oil is new and the gauge is now working, then the only other option is i'm burning oil somewhere. is there anyone out there that has experienced this problem before?

 

Were you low on oil before you changed it? If you were low enough on oil for the pressure to go down, you've pretty much ruined the engine by running it unlubed. The gauge is not an indicator of oil level, you have to check the dipstick.

On the other hand, if your oil level was fine, it's probably the oil pressure sending unit or the gauge going bad. I think I've read somewhere that the sending units are prone to failure.

 

Call Doug in the service department at Clear Lake Nissan (south Houston) and set up an appointment with Clint (username Latromi on this site). He is an excellent mechanic and the rates are very fair. He works on many Of the cars of the Houston area members, mine included.

 

I had opposite problem and ended up being oil pressure sending unit, but my best guess is you had low oil level causing slightly lower pressure reading