I have a 1998 jeep cherokee classic. It was purchased about a month ago. Well the oil pressure gauge was showing 40 when engine started and after it got hot it would drop to 10 at idle. So we replaced the sending unit. Nothing happened. Then our mechanic replaced the oil sensor and now it is reading 40-45 while running and once hot at idle it sits at 18-20. Is this normal?

 

Perfectly fine. You replaced the pressure sender twice?

 

No we replaced the sending unit once ourselves and our mechanic replaced the oil pressure sensor I believe.

 

you oil pressure sending unit is the sensor. The normal temp pressure minimum is 13psi so you are fine on pressure. One other thing, What brand of oil filter do you have? If you don't have a good quality filter on it, try changing it to either Mopar, Napa Gold or a Wix and you may see a slight pressure increase.

 

I'm not quit sure but I will check and see.