Fluctuating Oil Pressure and Idle

[Supercharged111]

I don't doubt there was sludge in there, I'm saying it's not getting as hot as you think to cause that. Have you ever owned a vehicle with an oil temp gauge? It's very educational.

 

[kennythewelder]

I am not trying to pic a fight or anything, I just wanted to know what you think causes oil to cake up like that if it not heat, and the oil is changed as it should be. I have lived in south Louisiana all my life. It is hot here most of the time. People I have worked with in the past, clam these same oils do not do this in colder climates. I have been told this by many people who have lived up north, but I do admit that this is hear say. So do you know what makes some oils do this, turn into sludge, and other oils under the same conditions do not turn into sludge ?

 

[Supercharged111]

Well the old school explanation I was given years ago was the Penzoil and Quaker State used a paraffin wax that, in a street car, caused deposits because they don't run hot enough. I'm sure that hasn't been the case for years now. My 1500 also had a little sludge caked in the intake valley and the lifters were gummed firmly in their position. I assumed cheap oil and crap intervals were to blame. My Z06 has 120k on the clock and is clean as a whistle inside. So is my Camaro and that routinely sees 300 degree oil temps. No yellow/brown, nothing inside. Just clean grey metal. The Camaro and Z06 both have oil temp gauges, this is why I say what I say as I have seen oil temps relative to coolant temps in both a street and track setting.

 

[livestrongroadie]

So this is becoming very educational, but I guess I was confused on what the gauge was. I thought the gauge I was talking about was oil pressure, but know that I think about the numbers it actually shows, I guess it would make much more sense that it is oil temperature.

 

[kennythewelder]

Your OE gauge is pressure, not temp. Also the OE gauges are not real accurate. They just give you a ball park reading. The thing is if there is a big change in readings. At idle 20 to 40 PSI is normal, and up to 80 PSI at say over 2500 RPSs or so is normal. When the engine is cold, the pressure will be higher, because the oil is thicker when it is cold. So if out of the blue, you see your OP drop to 5 or 10 PSI at idle, or if the pressure sky rockets, then there is an issue. If you go through the trouble of pulling a valve cover, you can see if there is a sludge problem or not. If there is a build up of sludge, then it will be through out the engine. If it is clean under the valve cover, the you can eliminate sludge as an issue.

 

[kennythewelder]

The sludge that was in my intake valley was a little like the sludge in this video.

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[livestrongroadie]

My gauge isn't so much the number it is reading that concerns me so much as how much is fluctuates while simply sitting there idling even after warmed up. I think I will get a video posted if I get the chance to see if maybe I am just chasing something that is normal for the old truck haha.

 

[livestrongroadie]

Ran a can of seafoam with a healthy drive and then changed the oil. Was going to see if any change happened but I noticed my radiator leaking badly all of the sudden, so guess I have to worry about this problem first haha.

 

[RichLo]

did nobody else catch that this is an 88 with only 66,000 miles on it? thats amazing! I be most if not all of your problems are from sitting unused rather than being used and abused.

 

[livestrongroadie]

Haha, this truck has been in my family since new and its true, it has spent alot of time sitting. I believe it's early life was spent as a farm truck, but from what I can tell, other than not being used, it was taken care of.