painkillerzz

I have been battling this issue for a couple days now.
https://my350z.com/forum/maintenance-and-repair/117216-no-oil-pressure-need-new-engine-i-need-some-info-and-assistance.html.

I took the car back yesterday, because I wanted them to take a look at it again for the low oil pressure at warm idle. My oil gauge read oil pressure at 5psi, and their equipment measured oil pressure at 7psi at warm idle. I thought, because of the post that I have read, that anything less than 15 psi would be bad. However, when the dealer called the Nissan tech line, they were told that 7psi is still "within specs". Nissan tech line stated that as long as the oil light is not coming on, there isn't a problem.


Has anyone gotten this response from Nissan on this low oil pressure issue. If so, is there anything I can referrence, if/when I speak to them? For those that stated that oil pressure less than 15psi would be bad, was this information received from Nissan, or where did you get that information. I am just looking for documentation that I can present to Nissan, if indeed 5 psi is not healthy for the Z's engine.

thanks

MA4

oil pressure is related to RPM's when you first start your car up the engine runs at higher rpm's to warm up the engine. once at normal operating temperature, the car will decrease the idle rpm's and your oil pressure will go down. When you step on the gas your rpms and oil pressure will increase. My 350Z's oil presure reading is exactly what you are describing and sounds normal. I did notice that my oil pressure will go below the 5psi mark around the time I am due for an oil change...probably because the oil is thickening up and becomes slightly harder to pump at low rpm's

painkillerzz

ok at least I am not the only one. It just happened all of a sudden, and wanted to be sure it was "normal"

Thanks

bwilliams

Normally, your oil pressure is a little higher when starting a cold engine for two reasons: 1) higher rpm, and 2) colder/thicker oil.
As car warms up, choke comes off and oil heats up and thins a little.
Older oil will be thinner due to chemical breakdown (yes, that's not a good thing) and therefore will result in lower oil pressure. It's a cue to change your oil.

I've never seen my oil pressure drop below 20psig, even after running hard in the summer. 5psig would concern me. If I had your condition, I'd make sure Nissan knew about it, in writing. I would also look at changing oil viscosity.

bknezevic

What's the recommened viscosity for a 350Z with around 4500 miles on it that lives in Georgia (90+ degree weather in the summer with humidity that makes it feel like its 110).

bwilliams

choice of engine oil viscosity, my viewpoint is:
For a fresh engine, i suggest sticking close to the sevice manual recomendations,
5W-30

Save the thicker stuff for over 50k miles (or over 80k if you treat the engine very well) when the bearings and bushings get a little more clearance.

bknezevic

So Castrol Mobil-1 Synthetic 5w30 is good then?? What brand should I get?

bwilliams

The brand of oil is not that critical as long as it's one of the main stream name brands. The time between changes will have a bigger difference in longevity of your engine.

GWAPITO69

iTrader: (6)

I don't pay attention to the oil pressure but today it seems kinda high when i rev to 3500rpm my rpm is above 60 is this normal for our car? sorry for the newbie question.

bwilliams

Your oil pressure sounds fine.
Mine does 25psi at idle, 75psi at 3000rpm cruzn. I never look at other rpms.

spn350z

FROM ERVICE MANUAL:
idle

spn350z

Oops.......
From ESM more than:
idle 98 kPa, 1.0 kg/cm2(square) or 14 psi
2000 rpm 294 kPa, 3.0 kg/cm2 or 43 psi
6000 392 kPa. 4.0 kg/cm2 or 57 psi

bknezevic

do you have 10w30 or 5w30...what was your break-in procedure like??

I just put in 5w30 Mobil Synthetic and its exactly as it was with regular oil...

bwilliams

I use 10W30 oil.
My break-in was mostly by the book (mileage and rpm).
Never over the rpm limit.
Very easy accel with an occassional brisk accel.
I kept this up for additional 2k miles (about a month) because I did a lot of highway driving. While on the highway, I changed speed a lot and would stop and rest every 20 miles.
My current oil consumption is less than half qt every 4k miles.

bknezevic

The 10w30 explains your higher oil pressure then.

bwilliams

Yes, it may explain a portion of the different oil pressure. I suspect most the difference is just difference in oil pump, sensor, transmitter, etc... many variables.