High Mileage Recommended Oil
 

Hi guy
Got a 07 HR with apprxo 140k miles on the clock
Been using the recommended Castrol 5w30.
However, i have notice a bit low on oil pressure recently as in photo (is this normal)
I have check for blown head gasket symptoms but nothing seems wrong

My question is should i use a thicker oil grade like 0w-40
https://cimg8.ibsrv.net/gimg/my350z....1d8bd146e5.jpg
3 to 4 minutes of engine running



https://cimg0.ibsrv.net/gimg/my350z....df5860d667.jpg
accelerating at @3000rpm





https://cimg1.ibsrv.net/gimg/my350z....b93c5086d9.jpg
warm idle after running for about 10 minutes Temperature is about 60*F
?
been searching on forums for a few days now

Any help would be much appreciated

A somewhat common problem with the HR, seems to be less prevalent on the 350Z, is the oil gallery gaskets. Nissan used a paper gasket that has a tendency to blow out and causes oil to leak back into the pan instead of lubricating the bearings and heads. Low oil pressure with no other symptoms can point to this.

Nissan specifies a minimum oil pressure of ~15 psi at idle (650 rpm) and 40 psi at 2000 rpm while using 5W30 and an oil temp of ~175F. I'm not completely sure on the temperature and pressures as I'm going by memory. You can find the exact numbers in the factory service manual. To test this you need a oil pressure test kit to hook up to the stock oil pressure sensor location. You can also use a wireless OBDII device and an android app called nissan data scan III to measure the oil temp.

As long as your oil pressures are higher than the miniums with 5W30 your fine. Moving to a thicker oil will increase the pressure but does not fix the problem. You may not be getting the oil flow to the critical surfaces that's needed even though your pressures are fine. This all being said people including myself have run the engines below the minimum idle oil pressure according to the interior gauge without issues but I don't recommend you do that for any length of time. My guess is that your oil pressures are borderline but fine. Keep an eye on it and test it if you have the tools.

One of my old 350Zs when fully warmed up also used to have the needle real low.

while rancor made great points I like to add the following:

- I dont know how many miles are on your oil but it might have started shearing down a bit.. this can result in lower pressures.
- I know a thing or two about physical organic chemistry (which what oil lubrication essentially is) ..its 2 am in my country I am going to bed and I dont want to type lengthy explanations.. But i always felt the recommended 5w-30 was a bit on the thin side for this engine.
The "5w" of it really isnt needed to be as low as "5" when temps are not low...a 10w-30 is inherently a more stable oil than an similarity formulated 5w-30 (less VIIs viscosity index improvers) and probably also offer (if all others things are equal) better lubricity since larger %age of the total formulation will be base lube due to fewer VIIs). 5w-30 generally need a better quality base stock to perform as well as a 10w-30.... I guess what I am saying is with it being summer in your hemisphere and especially with a higher mile motor dont be afraid to run 10w-40.
I ran my former FI'ed 350Zs (yes plural) on 0w-40 in winters, and 5w-40 in summers.

- FYI The USDM market demands that if a brand wants to test a vehicle for EPA purposes with a given oil it has to tell its buyer this oil is "preferred".. your at 140,000 miles all those original visocsities are out the window anyway.

(This does not preclude the possibilities rancor was talking about)

This. I was reading my service manual and it stated exactly what Rancor said. I've even sat in the car and revved it up to 2K RPM and it's well passed 30 psi, looks like it's about 45-50 psi to me, if I were to guess, all at operating temp. I've noticed that when I use the A/C or heater it likes to sit around 20 psi,when I'm cruising on the highway it's around 60 psi. I use Castrol Edge 5w-30.

What is the oil pressure suppose to be at WOT?

You never want to allow the oil pressure to drop too low because that can ruin your engine. Your engine can tolerate a compromised oil volume, but too low an oil pressure is disastrous.Using a heavier weight oil can help when the pressure is down, but this is just a weak "Band Aid."

If you are experiencing a varying oil pressure reading, it is likely due to a leaking (non-sealing) gasket. I experienced the problem recently, and the cause was a leaking valve cover gasket.

All great insight ... but before you go down a rabbit hole of diagnostics consider two things...

#1 - youre reading your oil pressure off a 10cent vanity gauge that has 4 incremental markings that span ~130 psi of pressure.

#2 - consider that your oil pressure sending unit may be on the way out.

It'd be smart to add a more reliable / accurate oil pressure gauge to truly diagnose the car off of.

I would agree that the gauge is not all that precise. I've got 2 hr engines, one since 50k, and one just over 100k. Your gauge reading looks normal to me, after the car is fully warm.

Yours looks to be reading about 0.5kpa which is roughly 8psi. Sure it's a little low according to the gauge, but as long as you dont have the low oil pressure light coming on, I don't see it as an issue.

Won't hurt to try a 0w 40. I switched to 0w 40 mobile one, which from research, pours thinner than other 40w oils. It did bump the pressure up just a bit, again, according to the gauge.

Eventually you would want to plan to replace the gallery gaskets with the upgraded metal ones, along with new oil pump if you choose. But if your oil psi is normal throughout the rpm range, I wouldn't worry about it.

What should the oil pressure be at WOT?

At WOT and higher than 5k-6,k rpm, the gauge reads right at 90psi.

The only time I've seen it above 90psi is on a low ambient temperature cold start. And never have I seen it reach 120psi.

I've been in your shoes, had the exact same readings. One (or both) of your gallery gaskets are blown. I wouldn't bother wasting time with 0w40 and oil pressure switch (although it's good to replace regardless - likely won't magically fix your extremely low oil pressure). Start planning to get those gaskets replaced.

Low oil pressure and the oil light came on
 

I have the same symptoms so I changed my sensor and it fixed the gauge took it for a drive pulled in my drive way and then my oil light came on I'm gonna be checking the oil again cuz I did it way to soon last light and oil was half way up the dip stick but and suggestions on what I could be dealing with

Gaskets be gone homeslice