I have a 90 'Vert

My oil pressure used to sit at 30 during idle and 60 when I was on the gas

Now it is at 45-50 at idle and still 60 when I am on the gas.

All variables are the same; oil filter is stock mazda, oil is Castrol GTX 20W-50.

I just changed the oil again and it is still like this.

Any ideas?

 

Have you checked the valves in the system? I forget what they are called now, pressure valves, one in the oil cooler, one in the front houseing and one in the e-shaft... did you check to make sure the oil pressure sensor is working correctly?

 

Yea maybe your oil cooler is pretty dirty... a car this old, im sure it needs cleaning.

 

If your having a problem with the thermal bypas pellet in the front of the eccentric shaft, your pressure would go down not up. The bypas valve in the oil cooler closes in colder weather, I not too sure of this, but that *might* make pressure go up, again, not entirely sure on this. Now for what I am sure of, that stock oil pressure guage is wierd! my spikes to above 100psi at idle, then it dives off below zero for extended periods of time. I have not seen it budge for months now. I drive the car *hard* everyday, the guage is totaly unreliable. try a mechanical guage if you are worried about it, but pressure going up is okay when its not too much high. I have seen as high as 50 psi at idle on a cold day with a different instrument cluster. It would drop slightly as temps came up and would come back up as the car idled in traffic and cooled in other ways.

 

Thanks for your input, all of you

The reason I am worried is because my gauge has been very reliable, reading 30 at idle and 60 on throttle for about a solid year. It has always been dead on.

Then suddenly a change.

That is why I worry.