So I rarely ever go on the highway but today I took a 45 minute drive. On the way back I noticed that my oil pressure was realllyyy low at stop lights, but went back up to normal when I began driving again. Anyone know what's wrong.

 

What's your oil pressure?What's low? Hot idle is 13 psi at 600 rpm, and it's 37 -75 psi above 1600 rpm.

 

details!? There is a rule of thumb to follow here, but I cant remember it. I think 20 is average at idle, and up to about 60 at highway speed.

 

Maxwedge is correct, 13 @ idle, higher at speed.

Ron

 

When was the last time you did an oil change? How about even checked the oil?

It could also be that the sending unit for the gauge is going bad. They are known to be complete crap, and tend to break often.

 

Ok oil changes have been regular, changed it last not even 1000 miles ago. The pressure was on the first tick on the gauge and it is usually in the middle. I let her sit for a couple hours and then drove it again and it seemed to be a lot better, it only got barely below the half way point on the gauge, even when stopped so we might be ok but I still wonder what happened.

 

Thanks for the responses btw.

 

What brand of oil filter are you using? Certain brands have been known to come apart internally.

 

Not positive actually. But the pressure seems like normal today.

 

Don't get lazy. You need a good filter on there.

 

My '98 XJ with around 180k on the clock has done the same thing for probably a decade. After driving for over an hour, when it comes to a full stop the oil gauge needle will be setting on the very first hash mark. Could be the sending unit but I/m too lazy to check. I've used various oil & different filters and it has never changed. In cold weather the oil pressure won't go quite as low. Engine runs strong and as quiet as any 4.0 is gonna run.

 

My 99 and 97 had the same issue it was the sensor, and I wasnt having any preassure issues. I would still have it checked or hook up a tester direct to make sure, but if its running strong I doubt you have anything to worry about.

 

Mines a 98 too. That is exactly what happened to mine.