so for a while now, i would notice that my oil pressure gauge would always be high after a fresh oil change, i would step on it, and the gauge would go near to 120 psi. however after driving it through time i would notice it wouldnt go as high. i mentioned it to my mechanic friend and he said it was just the oil getting hot and thinner. how ever with my last oil change which was about 2k ago, it was filled about 3/4 of the way on the measurement part of the dipstick. i checked it this morning and it was a just above the Low point and the oil still looked golden brown, not even black. My question is what is happening? at first i thought maybe a leak, but there never a puddle under my car or drips. Maybe burning? but my car never smokes and it never smells like burning oil. If someone has any information or has been through this, plz put some input this is my baby which im barley about to slam, and its my daily driver.... wanna make sure this isnt a major problem, before i spend my money on coils and wheels.

extra information: currently when i cruise the car on cruise control at 70 mph the oil pressure gauge is at the 60psi marker
when engine is fully warmed up the idle is right under 30psi(the side of arrow barley touches 30 psi line.
i change my oil every 3k-3.5..... and i use Mobile1 5w-30

 

The obvious first question would be...
What year is your Z?By any chance a 06?
Have any black deposits around your tailpipe tips?
Oil consumption with no physical signs,smoke,
puddles under the car,is usually caused by blow by.
There are two schools of thought on the use of synthetic
oils like Mobil 1.This oil is much thinner.Thus,passage through seals
can occur.Positives are that it lasts longer.Does'nt break down.
Guys think by adding Mobil 1 their car is gonna run faster.
Check the posts of new owners that immediately change the oil to
Mobil1.They have no knowledge of what oil was previously used in the car.
But they think its a "magic bullet " of sorts.At times the bullet is
what you are experiencing

 

not to sure what blow by means?
sorry to mention that, my car is 2003, and has 120k on it. i bought it 2.5 years ago with 70k, never had problems with it.... the car still run like a champ though! no complaints about perfromance, just worried about this problem before my performance does get jacked....

like i said i change my oil around every 3k so i really dont care about it lasting long, and i dont race my car, just when me and some friends get bored while a cruise or something

 

Blow by(oil)is oil being pushed through various seals&gaskets,rings in the engine.It can also occur through poor crankcase ventilation...PCV in cars that have them.Oil can be sucked through the intake in the filter area or the manifold.Sounds as though something is just wore out.120k miles on a VQ engine with proper care is not really a high number.Your oil pressure drops thats a sign of a internal leak.I'd get a compression test.Also,you are using
a full synthetic-Mobil1 and changing every 3k miles?Not really necessary.
If it were me,first thing I'd do is change to a heavier oil.Possibly a 5w30
semi-synthetic for hi-mileage cars.I also have a 03 Z.Not at your miles.Mine
is at 79k.Bought new.Have used Valvoline SEMI-SYNTHETIC.Change oil
5-6K.Use a Nissan filter.Uses no oil between changes....Maybe 1/2 qt
to top up if I want to.Perfect oil pressure.

 

ahhh ok i get you.... my friend (which is a mechanic) mentioned something like that but we ended up changing subject during that conversation.... ill have him take a look at it. i hope its something minor thats not to pricey, or that will cause damage.
but about changing oil, isnt it bad to change to certain oil, viscosity wise, or type?

 

For now,you just need to make sure you have the proper oil level in your car.I'm afraid that the fix will be "pricey".It depends what pricey means to you.If you are adding a qt every now &then and your car is running fine,you may have to weigh the trade off of a fix that may be quite costly and adding those qts. of oil.Problems like this will not get better.They will get worse.
I think you are a bit paranoid about changing oil.The Z calls for a 5w30 oil.
You could use(IMO)a 10w30 and your car won't blow up.Also,again if it were me,given the symptoms of your problem,I'd get off a full synthetic to semi or even conventional.Your logic of chaging oils makes no sense as you don't know what the previous owner/owners used.They may have taken it to Wal*
Mart for all you know.

 

Motor oil can only go one of two places:

Burn it in the combustion chamber
or leaks on the ground.

A leak is easy to diagnose: park the car overnight on newspaper. If the newspaper is soiled in the morning you know that the motor is leaking somewhere.

 

I blame it on driving habit

 

I have a a pretty clean drive way, I would have noticed some sort of leakage. But I'll try the newspaper.

 

Driving habit? Haha

 

Get off that redline dude!

 

Ahhhh haha.... Nah I don't redline man, like I said its my daily driver I dont race it.... And when I do ( which is really rare) I stay under redline, too scared of breaking something. I need one more year of college cant afford to lose my car haha

 

That sounded totally dumb when I put that.... Haha just meant to say that I keep Car maintenance every three 3k. Did mean to sound like dumbass.