96 Country 4.0L 4WD, 265K

Last 100K or so, I've been using Mobile High Mileage 5W30 or 10W40, depending on the season - main seal is leaking a little. The engine probably leaks .75 quart and uses .25 quart in 3,000 miles. I have typically gone 4.5K to 5K between oil changes.

When the oil gets up to 3K service, the oil pressure can start giving very high readings - never quite pegged to the right but up to 70 psi. It's rpm sensitive and seems to have a mind of it's own. Could/would the "seal" additive in the oil cause separation of the oil into heavier vs light components (and the heavier, thicker strata being obviously at the bottom and what gets into the oil pump). It takes a while running at highway speeds (maybe 30 minutes) for the problems to occur.

Just changed oil and went to straight Quaker State to see it it would make a difference but thought I'd ask of anyone else has had this experience.

Thanks in advance,
Larry

 

might be time to replace the oil pressure sending unit.

 

 

X2 on the sending unit. Mine fluctuates as well, but mainly under acceleration and before it's fully warmed up, it'll spike to 80 and sit there as long as I'm hitting the gas. I let off or the engine has warmed up and it'll sit at 40, only moving slightly.

 

I agree that the oil pressure sending unit itself could be on it's way out.

I'd replace it and I'd do so with a Mopar sending unit purchased directly from Jeep for the best reliability/accuracy/mating with your factory gauge. They aren't particularly expensive and are easy to replace.

Good luck and keep us posted!

 

What brand of oil filter are you using?

 

I use the basic Fram filter - probably should upgrade. I don't think the problem is the sending unit. I gathered 3 stock units at P n P and they all do the same thing.

 

Worst filter you could use.

Just swap filters now and see what happens. Napa and O'Reilly's carry Wix.

 

Thanks for the advice. I'll do the filter upgrade on the next oil change. For now I'm going to hold the variables to one item - the change in the oil. If one changes multiple things at the same time and it fixes the problem, you don't know what the culprit was.

Alternatively, maybe it's your view that the filter has nothing to do with the erratic oil pressure and one should go ahead and upgrade because it's not going to impact the problem/mystery?

Viewed the video - nothing new there.

 

I'm thinking the filter has EVERYTHING to do with the issue.

 

Well folks, I do believe that cruiser was right on the money. During the first 1k of the Quaker State oil, same erratic oil pressure. So after about 1K, I pulled the Fram and replaced with Wix. Since then there has been some very slight variability of OP but nothing like before - probably all temperature related. The OP hasn't been over 55 at operating temperature since I put the Wix on. THANK YOU CRUISER.

So get rid of those Fram oil filters and put a quality one on. Wix seems to work.

 

Another person saved from the FRAM car killer

 

LOL. Fram is JUNK.

I'm really glad that worked out for you and a huge THANKS for reporting back.