What is the proper oil pressure for a 2001 Grand Cherokee with a 4.0 I6? What should it be at idle? What should it be under operation?

RIZ

 

13 psi or > at idle My '04 with 95k has only 4 psi at idle and bugs the heck out of me every time the check gages light and chime come on but it runs like a sewing machine!
Thicker oil will increase pressure but that does not accomplish any good.....oil flow is what you need. Low pressure is most likely caused by worn clearances and additives or thick oil won't solve a thing other than giving you higher pressure and a false sense of hope.

 

A "safe " bet on any engine is 10psi per thousand rpm, not ideal but safe. My 4.0 runs 25 psi at a 900 rpm idle and about 50-70 psi while crusing, but its a low low mileage engine.

 

Do you have hi miles, a bad leak or a faulty gauge? Ever hear it ticking? Oil change history?

 

I've got around 125k on it. I just did an oil change over the weekend and prior to it I was running at 40 psi both at idle and operating but occassionally I would see it drop to around 10 psi at idle but would always sit at 40 psi under operting. I swapped a much bigger diameter wix filter from what the previos owner had on there. So far since the oil and filter change I've been running at 45-50 psi...... it's only been the last couple days so the 10 psi at idle may pop up again but hasn't so far. It runs smooth and never hear it ticking but I was just wondering what it should be.

RIZ

 

Hmmm, I only run wix filters and have actually seen them raise oil pressure since they are made tighter than any other filter, I wonder if the oil pump is going. Since it will be 40 then just drop to 10.

 

A restricted oil filter will LOWER oil pressure on a 2001 4.0 because the oil sending unit is downstream of the filter.