Hey,

I have searched through many threads and I haven't been able to find an answer. I bought my 2003 350z not noticing that my oil pressure needle was over 120 psi at all times. I later found out that it was the oil pressure sensor and so I replaced it. After replacing it, during cold starts it would get up to 60 but when the car is warm the pressure drops to a little above 0-10 psi. I have tried many forums but can't seem to find an answer. When accelerating the pressure does rise but drops to zero when idling and then the oil light comes on.

I just replaced my oil and filter and there is no leaks that I can see. I don't have any engine knock or unusual sounds. And again I also just replaced the oil pressure sensor.

i read that the gauge is inaccurate but would it be that bad that the pressure goes down to zero?

 

If you've got a low gauge, and a low pressure light, I think you've got a problem. What oil are you using?

 

Castrol edge 10w-30. The oil light does go away when I accelerate though. It comes on after idling

 

I would take the car to a Nissan dealer and have them install their mechanical guage to get an accurate assessment of the engine.

 

If you are not leaking oil it sounds like the internal oil gallery gaskets might have failed, but I didn't think this was a problem with the DE.

 

Yeah I've read about it but it said that if that was the issue then at idle the cars rpm should slightly drop. My cars idle stays at a 750 constantly.

 

[QUOTE=dcains;10777826]I would take the car to a Nissan dealer and have them install their mechanical guage to get an accurate assessment of the engine.

Thanks. My friend has a mechanical oil gauge so I'm going to try that this weekend.

 

Be very careful with the threads on the oil pan fitting. It's a tapered pipe thread, and if you tighten it too much, you'll crack the pan.

 

I actually just went through this very same diagnostic on my twin turbo car. Oil light would come on after it was hot and idling. First I had the exact same symptoms gauge in-op stuck at 120. Installed new sensor and oil change to 5w-30 Mobil 1 oil and filter. A short time after I purchased an AEM oil pressure gauge to check to see if I actually had low oil pressure. And sure enough it would dip to 8-10 psi at idle when hot on the AEM gauge. I did some research and switched oil to royal purple 10w-40 and used an OEM filter. This did improve oil pressure it was steady around 14 psi at idle which is within spec. Recently I added a mishimoto 19 row oil cooler and thermostatic plate adapter. I Moved the Aem sensor to the plate adapter cause I had the factory sensor disconnected. Now my oil psi is around 25-30 at a hot idle. The weird part is that the factory oil psi sensor does read about 10-15 psi less than the AEM gauge. My first theory was that with the turbo oil feeds being plumbed into the same port as the oil psi sensor it was increasing flow which would cause decreased pressure. I'm still not sure if the car ever actually had low oil pressure but it's 100% fine now. Also my car has a fully built sleeved block with rods pistons new oil pump and new bearings.