Im getting 40psi oil pressure under a load and only 20 stopped in drive....

Aureliametal · 11-21-2009, 09:18 PM

Is this going to blow my engine up? I was gonna try some lucas to thicken the oil up. Good idea? Thanks, Joe

Travis873o · 11-21-2009, 09:20 PM

that's normal.

you're oil pressure is supposed to regulate like that.

Sextiva · 11-21-2009, 09:37 PM

I think he is reffering to the abnormally low pressure reading. Check your oil first if you haven't, and then I would look at your oil pressure sending unit. Those are a pretty common failure in older vehicles, and if it is that then the reading at your gauge is false. If that isn't the problem I would drop the oil pan and replace the screen on the pump. If that isn't the fix then prolly the oil pump. Gl

**UltimatE** · 11-21-2009, 09:52 PM

Do not add lucas...ever.

Aureliametal · 11-21-2009, 11:33 PM

Ok, so if I let it idle at 20 psi for any kind of period of time will it do any damage? And why no lucas? I have always sworn by that stuff.

**ratmonkey** · 11-21-2009, 11:38 PM

Anything over 10psi at idle is good and requires no action.

Mopargearhead · 11-22-2009, 01:30 AM

If you want to make sure you have good pressure hook up a mechanical gauge and check. The oil pressure gauge in your Jeep is not accurate by any means.

colt808 · 11-22-2009, 01:45 AM

x2 on testing the sending unit and using a mechanical guage

But I doubt there's anything wrong. If there was a problem, the idiot light and CEL would come on.

StuntmanRyan · 11-22-2009, 06:40 AM

is this after the engine has been warmed up or is this under cold startup that you are only getting 20psi

1995zj · 11-22-2009, 07:41 AM

Quote:

Originally Posted by UltimatE

Do not add lucas...ever.

Why is that?

**UltimatE** · 11-22-2009, 09:10 AM

What about Additives?

1995zj · 11-22-2009, 10:35 AM

Quote:

Originally Posted by UltimatE

What about Additives?

What about at operating temperature? I see he is testing lucas additive at room temp. But the oil is much thinner at operating temp and I don't think their would be as much frothing at operating temp or any.

Aureliametal · 11-22-2009, 02:26 PM

I just changed the oil with 10w30 penz. No additives. Its getting 20 psi at idle after its warmed up.

1995zj · 11-22-2009, 03:17 PM

I average about 70 before warmed up, about 35-40 after warmed up at idle and about 55-60 while driving

TMCXJ · 11-22-2009, 04:32 PM

Agreed - 20 at idle is NOT "low."

I had a 91 XJ with the 4.0 HO and at idle in drive it would go below 10. It was never a problem.

If you're that worried about it, do as recommended and use a mechanical guage. Otherwise, take the advice of others and call it good - 'cuz it IS good.