My XJ appears to have ok oil pressure.I just need to know if what I see is acceptable.
At speed I'm running right at what appears to be 40 psi. At idle it drops to around 20 psi. Are these readings acceptable?

When I take off from a stop,it will move over to 60 psi,and anytime the tranny shifts,the gauge drops a little.

Is the gauge supposed to fluctuate with the rpm's?

 

More movement in the engine is higher pressure built. I think. I hope. Lol mine does the same.

 

Lol mine does it too. I think the higher the rpm's the more the oil pressure goes up. Lol that's bout all I know about that lol

 

That's good as long as it never gets under 10psi you'll be alright. Those are normal readings

 

A general old school rule of thumb is 15psi idle and 10psi per 1000rpm after that.

 

Thanks not meaning to hijack , I just learning something new

 

I beleive its supposed to be reading 12-20 at idle and 40-50 while running. Mine flucuates as well.. But it never gets to 60... Maybe its time to change my oil, Shes steadily at 40-50

 

Factory spec for the 4.0 is as follows:

*Not less than 13 psi at HOT idle

*Between 37-75 psi over 1600 rpms

And yes, oil pressure will always fluctuate depending on how much throttle is tipped in..

 

This is what my experience and readings has been.

 

I just did an oil change and I beleive it had 10w-30 and I put in 5w-30 and it dropped from 30-40idle to 15-20...so that might have something to do with it or i just have a weird 4.0...