blackz28x07

My car is a 98 with 97K miles, and I use pennzoil platinum 5W30. Cold start on my car is 60 psi, when it get's up to operating temp it's 40 psi, and warm idle it's about 30 psi. Well when i'm in a lot of city driving my oil pressure drops pretty quickly. When I'm slowing down and I'm almost at a complete stop the engine is at 850 rpms and the oil pressure is at 30 psi. When i am at a complete stop at an idle, 750 rpms, my pressure drops another 5 psi. I just thought it was weird it would drop 5 psi when the rpms only dropped 100 rpms. I don't think it's a major issue since the oil pressure rises with the rpms, and at 1500-1700 the oil pressure is at 40-42, and cruising on the highway is about 55. Does anyone know why it would drop that much just from a 100 rpm difference? Could it just be the gauge?

fleetmgr

two possibilites:
1. Nothing at all wrong.
2. Put a gauge on it. If it tracks reasonably close to the dash, see #1. If it doesn't, put a new sending unit in.

THE SHOP

Yous gauge is not all that exact put a mechanical gauge on it.

blackz28x07

I know the gauge isn't that exact, just thought it was weird.

Viper

iTrader: (6)

Mine does that too, and at idle it will actually oscillate a little. I'll probably replace the sending unit soon.

Sykokilla

iTrader: (4)

Same as viper. I actually had your problem and replaced the sending unit and it still acts goofy. I will get it on a guage soon enough for assurance.

The02Witchburner

Have you noticed any ticking noises on the highway or after sustaining 2,000 rpm's for a while?

Viper

iTrader: (6)

I have not, just the usual impossible to seal little exhaust leaks.

blackz28x07

There's no problems with ticking. My gauge does a lot of little weird things. On the highway if i have my foot off the gas it's about 50 psi, but when i put in on the gas just to keep a constant speed, not accelerating, the psi will drop to about 47. F body's are just weird like that I guess lol. I doubt it's anything major though, at WOT it goes up to 60, and when just cruising it's at least 40 or higher. Just curious if it could just be a gauge thing or not.

The Mighty Texan

iTrader: (4)

I have something similar to this problem too, except i notice when driving that the gauge fluctuates between 40 and 50 psi when my oil is low and needs a quart or so. Is it normal to have to add that much between oil changes? Does anyone else usually end up having to add oil before changes?

THE SHOP

Have you changed your pcv?

The Mighty Texan

iTrader: (4)

Not that i know of, I know i haven't but the owner before me might have..

1 FMF

iTrader: (1)

in traffic there's little airflow through the radiator, and i'll bet your radiator fans are kicking on automatically which means coolant temp is over 220F. As a result, your oil temp is around 220-250F and as temp goes up oil viscosity goes down, resulting in lower oil pressure especially at lower rpms. What you describe is normal and expected for a 5w-30 oil on an engine with 97k miles at low rpms. When the pressure doesn't jump over 30 psi at 2000 rpm when the engine is hot then you have problems.

and the oil pressure gauge is accurate. stop saying they are not accurate or not exact,
a mechanical guage is "not that exact"!

Facelift

So my gauge reading just above 20 all the time is probably not a good thing regardless of full throttle or idle. Awwww pewp

91RS383

The PCV comment was about the oil consumption question.

Have you tried a diffent brand of oil? Maybe Castrol or Mobil won't lose it's viscosity when your motor gets hot.

blackz28x07

Mobile 1 5W30 or 10W30 thins out quickly to a 20 weight when it gets hot. I had even lower oil pressure with the mobile 1. I picked up about 3-4 psi at hot temps with the pennzoil platinum. I'm going to try German castrol next to see what it does.

91RS383

From what I've read GC is closer to a 40W. I like it so far in my Turbo Sky, but it was too thin over-night in my old school Jeep 4.0L and I had lifters deflate a couple of times when she sat for few days.

blackz28x07

My car doesn't usually sit for very long. The longest it usually sits is overnight for about 10-12 hours. I've just read a lot of good stuff about GC, so I thought I'd try it this summer.