I was just watching it on and off as I was driving, noticing the needle rise and fall ect and wondered whats the actual point of having it, I think its cool eye candy but should I be keeping a tab on it if it goes too high or low?

 

I use it to judge how warm my car is. The water temp can be normal while the oil temp is still low. I don't go above 3K until the oil pressure sits at 30 or below when idling.

 

its a pressure gauge, not temp gauge... but I guess if you can gauge temp from the pressure sure.

its very sensitive, I saw mine get real close to 120 the other day, and then come right back down to the bottom half after that. kinda odd

generally means very little to me tho. if it showed nothing Id know something was amiss I guess.

 

I use it to determine when the car is actually warmed up enough to drive hard.

Generally for the first 5 mins of driving (after being off for a while) you'll peak the pressure if you take it over 3-4k while the engine oil is still cold.

 

thanks for the info!

 

I check the oil gauge occassionally to make sure my engine is running right and to avoid any major problems. Basically, you only have to worry if you have no pressure or very low pressure. High pressure is rarely a problem unless it occurs all the time.

In idle or low rpms oil pressure should be around 30 psi
Under normal conditions 45-75 psi
Under high stress up to 90 psi
It is OK if it spikes really high as long as it comes back down.

If you are getting low pressure or no pressure, you should get you engine checked to avoid major damage. Also check the engine if oil pressure is constantly high when not stressed.


The other gauge is the voltmeter. That gauge checks your electrical system. Under normal electrical load it should be around 14 volts. Of course adding other electrical doodads will load the system but, as long as you stay above 12.5-13 volts you are fine. When you start dropping below 12 volts you are using more electricity than you are generating. You should start unplugging unnecessary electrical equipment. (i.e. cellphones, radar detectors, computers, etc.). If you are still below 12 volts take your car to a service station and have your electrical system checked. If your battery is fairly strong, you should have about 1 to 1.5 hours of life in your battery before it dies. If your voltmeter is reading below 10 volts, DO NOT TURN YOUR ENGINE OFF because you will not be able to restart it. Get the cars electrical checked ASAP. If you are getting constantly high voltage spikes, check the systems grounding and/or look for shorts.

Hope this helped.

 

You can sort of use it as a temp gauge. In general, barring any other problems, when the oil is hotter the pressure goes up and when it is cooler the pressure is down.

A better way to gauge engine temperature is to use the gauge with the Engine Temp picture on it. It's the one by the Fuel Gauge! And if you can't read that gauge, you should have your license revoked!

 

wish the oil gauge was a stock turbo boost meter for a twin turbo 350z..

sigh

 

You can always get an aftermarket turbo boost gauge and claim that you have a quad turbo 350Z. Just remeber it ain't cool unless it's at least twice the size of your speedometer and blocks your view out the front left side. That mod should cost about $15 and take about 30 minutes to install.

 

Aggro, I think you have that reversed......pressure is higher when cold & thick, lower when hot & more vicious.

Now, if someone would share info on where to mount an oil temp sensor, this silliness could stop!

 

EthuZ, you're right I do have it backwards. My bad.

 

I'll forgive you..........this time!

BUT, about you're spelling of my handle..........

 

i tried to correlate the oil press to my oil temp, but eh. not so lucky.

at 60psi, i got around 90*C temps...
but even at slow drives around town ~45psi, the temps were still the same...

oil pressure is good to know if you got boosted and say a return line for the turbos popped off and you were leaking oil, then a low oil pressure would be an indication for trouble (knock on wood!!!)

what i wouldnt mind is a fuel pressure gauge!

 

PV=nRT. All other variables constant, pressure increases with temperature. Viscosity decreases with increasing temperature. Just my two cents.

 

kvjacobz

I think both you and EnthuZ(got it right this time) are both right. I believe the gauge measures the pressure that the oil pump exerts to keep the oil flowing at given flow rate.

When the oil is cold, it is denser and thicker, thus requiring the pump to work harder to keep the oil flowing. As the temp rises, the oil becomes less dense and more fluid. The pump has to work less to keep the oil flowing. This shows up as less PSI on the gauge.

PV=nRT is correct, so you might think what gives? Oil is a fluid not a gas.

Anyway, the Oil Pressure Gauge is just eye candy on a new car. Most people don't know how to use it and it is something that can be monitored electronically by engine management. If you really want to know how to use it, see my earlier post on this thread.

 

Since I got my Z the volt meter stayed pretty consistantly at 14 volts. I noticed that after I installed my grounding kit, and started the engine, it was reading 15 volts for a while (about 30 minutes). Eventually it went back down to 14 and has stayed there since (about 3 days now). Does that sound normal?

-Chrismcagle

 

Sounds like it fixed itself. Maybe the electrical system just needed a break-in period after installing the grounding kit. If nobody else experienced the same thing and it goes back up, get it checked out. Better safe than sorry.

 

Wow, this board never ceases to amaze me.

Do you realize that you just quoted the ideal *GAS* law as an explanation to pressure changes in an *OIL* system?

Jesus, people will really say just about anything, won't they?

Jason

 

Beat me to it!

Fluids have a much more complex expansion pattern, especially hydrocarbons such as oil.

 

Hey, don't forget that engine oil is designed to be LESS viscous at cold temps, hence the w rating.

If you want pressure to correlate to temperature, you're going to need to run a single weight oil.