Oil Pressure Question

[Joe Blogs]

I know there have been numerous threads previously about oil pressure. However, I'm going to throw in a twist. My TJ is an export Model 2002 Sahara. When I start it up in the morning the oil pressure seems quite high and the faster I go, the higher it seems to get. After about 10 minutes of driving, it seems to reduce to more of a mid range on the gauge. There have been previous answers about dirty oil filters and the need for oil change and I'm guessing that's where I may be at.

However, here's the twist...Is my gauge showing bars unlike the US version that would be in Lbs and if so...Is the reading shown very high?

 

[JKP]

Depends on how cold it is and the weight of the oil you are running.

Oil pump relief valve is set at 75 PSI, IIRC.

 

[CharlesHS]

Do you know if someone replaced the oil pressure sending unit around the time this started happening?
The new oil pressure sending unit may be for the wrong application.

 

[iamloganjames]

I don't know about the metric vs lbs conversion. But in the mornings, i have to let my 4.0 idle for quite a while before driving. otherwise the oil pressure will climb all the way to 80 about 1500 rpm. This is at about 40-50 degrees F. With 10w-30 oil. I get around this by allowing extra time in the morning for the jeep to idle and get up to temp. If i ran the 5w-30 oil, then my oil pressure would be way too low in our 115 degree F summers.

 

[pagrey]

The picture shows about 60 psi. 80 psi is 5.5 or a bit over max on this gauge. Our gauges show 0 - 40 - 80 in our units and that's really the same as 0 - 3 - 5.4 if that helps. A dirty filter wont do anything but bypass the filter generally, it might lower the pressure somewhat but wont raise it. If it's between the top and bottom it's probably fine. Ireland is cold, you shouldn't be running heavy oil, pay close attention to the temperature ranges of the suggested oils and stick with that.

 

[Fishtaco]

I don't know about the metric vs lbs conversion. But in the mornings, i have to let my 4.0 idle for quite a while before driving. otherwise the oil pressure will climb all the way to 80 about 1500 rpm. This is at about 40-50 degrees F. With 10w-30 oil. I get around this by allowing extra time in the morning for the jeep to idle and get up to temp. If i ran the 5w-30 oil, then my oil pressure would be way too low in our 115 degree F summers.

Thats why you run 5w-30 in winter and 10w-30 in summer I would presume?

 

[Fishtaco]

The picture shows about 60 psi. 80 psi is 5.5 or a bit over max on this gauge. Our gauges show 0 - 40 - 80 in our units and that's really the same as 0 - 3 - 5.4 if that helps. A dirty filter wont do anything but bypass the filter generally, it might lower the pressure somewhat but wont raise it. If it's between the top and bottom it's probably fine. Ireland is cold, you shouldn't be running heavy oil, pay close attention to the temperature ranges of the suggested oils and stick with that.

Strange Aussie imports show PSI I would have thought Jap imports would have had the same gauge?

 

[pagrey]

Strange Aussie imports show PSI

What are your tire pressure gauges like?

 

[iamloganjames]

Thats why you run 5w-30 in winter and 10w-30 in summer I would presume?

Nope. I just run 10w-30 all year round. Temps get into the 70-80s even in the winter here. It's only cold in the mornings after the sun's been down all night.

 

[SkylinesSuck]

I know there have been numerous threads previously about oil pressure. However, I'm going to throw in a twist. My TJ is an export Model 2002 Sahara. When I start it up in the morning the oil pressure seems quite high and the faster I go, the higher it seems to get. After about 10 minutes of driving, it seems to reduce to more of a mid range on the gauge. There have been previous answers about dirty oil filters and the need for oil change and I'm guessing that's where I may be at.

However, here's the twist...Is my gauge showing bars unlike the US version that would be in Lbs and if so...Is the reading shown very high?

View attachment 315028

You are describing the normal operation of how it's supposed to work. Totally normal. Oil is thicker when cold and thins out as it warms up. Your worrying about it is why Jeep turned it in to a glorified idiot light in later models.

 

[bromel]

Oil thins as the engine warms up, so the pressure decreases. Per the operator's manual, as long as your hot idle is greater than 13 psi (or a little less than 1 bar), then you're fine. Don't overthink it.

 

[Fishtaco]

Nope. I just run 10w-30 all year round. Temps get into the 70-80s even in the winter here. It's only cold in the mornings after the sun's been down all night.

Yes but the 5-W is for winter start up viscosity its still 30 weight after warm up no matter the W rating so if it isn't that cold in your area then the outside temperature cant affect your oil pressure because the flow is correct from start up.

 

[Fishtaco]

What are your tire pressure gauges like?

We have both PSI and Bar on tyres and air pumps not sure anyone even knows what Bar is? Its a bit like some other measurements even though we have been metric for donkey years everyone can fairly accurately call out a person over 6' and never say over 180cm same as Tyre pressure 28psi never?? Bar lol

 

[Fishtaco]

You are describing the normal operation of how it's supposed to work. Totally normal. Oil is thicker when cold and thins out as it warms up. Your worrying about it is why Jeep turned it in to a glorified idiot light in later models.

Unless my 06 is stuffed it gradually goes up to half way when started (less than 2 secs) and stays at half way while driving unless I accelerate hard then it goes up to between half way and full? Idiot gauge electrical fault?

 

[Joe Blogs]

Great answers guys. Thank you all for the input.

I will be doing an oil change in the next few weeks. What grade oil would you guys recommend for the Irish climate? The same oil will be in it all year round and it's very mild here.

 

[pagrey]

10w-30 is fine if it doesn't get really cold, below 0F or -18C. If 15w-40 is cheaper and easier to get that's also fine for a high mileage Jeep especially in mild weather.

 

[SkylinesSuck]

Unless my 06 is stuffed it gradually goes up to half way when started (less than 2 secs) and stays at half way while driving unless I accelerate hard then it goes up to between half way and full? Idiot gauge electrical fault?

That's the idiot light version. People were getting scared when they saw it dip down to 1 bar/15 psi at hot idle.

I have the old gauge. At cold idle, it reads about 60 and if I blip the throttle it goes up to around 70'ish but never higher because of the pressure relief valve in the pump. At hot idle it's around 20 psi but if I rev it up I can get it up to around 60 psi fairly easily.