funny oil pressure (long)

ncwheeler · Dec 19, 2005

I have a '98 4.0l with 128k miles, its been pretty well taken care of and had regular oil changes. Starting this summer I had put 10w30 in it for some reason, prior to that I had always run 10w40. A few weeks after the oil change the pressure started to drop to 20psi at idle (which is about 500-600 for me). After I had driven for about 20 minutes but as soon as I got on the gas it would go up to about 50psi and drop down to 40psi at about 45mph (1500rpm). I figured this was just normal and figured Id just put the 10w40 in it the next time I changed my oil. I changed the oil about a month ago and ever since it has gotten worse. Its stays around 40psi until I have been driving for about 15-20 minutes. Then starts to drop to 20 at idle, still not a problem. However, then it drops down even lower to right at 13psi. I know that some of you say this is fine, but it has never done it before. What do yall think the problem is?

hippymill · Dec 19, 2005

are you reading pressure off the stock gauge? If so don't rely on it. If you want accurate oil pressure, get a mechanical guage. Only way to tell for sure.

BCParker · Dec 19, 2005

ncwheeler said:
I have a '98 4.0l with 128k miles, its been pretty well taken care of and had regular oil changes. Starting this summer I had put 10w30 in it for some reason, prior to that I had always run 10w40. A few weeks after the oil change the pressure started to drop to 20psi at idle (which is about 500-600 for me). After I had driven for about 20 minutes but as soon as I got on the gas it would go up to about 50psi and drop down to 40psi at about 45mph (1500rpm). I figured this was just normal and figured Id just put the 10w40 in it the next time I changed my oil. I changed the oil about a month ago and ever since it has gotten worse. Its stays around 40psi until I have been driving for about 15-20 minutes. Then starts to drop to 20 at idle, still not a problem. However, then it drops down even lower to right at 13psi. I know that some of you say this is fine, but it has never done it before. What do yall think the problem is?

you're describing my problem exactly, same milage, same pressures, except I've always used 10w30-
like said above, the oil pressure sender/gauge isn't the most accurate, for example, simply by unplugging and blowing on the connection, then plugging back in gained me 10 PSI.

on the subject of the aftermarket gauge, how would one go about hooking that up, and how accurate will that be- any reccomendations on a brand or setup that has worked for you?

stewie · Dec 27, 2005

hate to bring back to life a old thread, if you conside a week old. 1995, 4.0, auto, 182000 miles. i am having problems similar to those above. according to the stock ail pressure guage, at idle it dips down to 20 and under acceleration it skyrockets to 60-80++++. i have seen the needle even with the screw that shows through the guage face. this is worst under heavy acceleration (passing, and getting on the freeway) and it is quite un-nerving. any imput would be much apreciated

stewie

summitlt · Dec 28, 2005

My truck did the SAME thing as above, looks like you were in my truck when I drove it. I went and got a new sender ($20) and put dielectric grease on teh connection. Went back to normal, and went with the readings I got from a mech guage.

funny oil pressure (long)

ncwheeler

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hippymill

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BCParker

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stewie

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summitlt

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