High oil pressure with STP filter - - -

[GMBoy]

I had a very unusual experience just recently. With my wife's 2001 Olds Aurora 4.0 (the V8 model) I have always used Mobil 1 and an AC Delco oil filter with changes around 4-5,000 miles. The last oil change the store was sold out of AC filters so I used an STP filter. Around 3,400 miles on the oil the pressure shot up to over 100 lbs as indicated on the digital DIC screen. Even going slow it was still hovering around 85lbs. I immediatly went home and changed the oil and filter and the problem was instantly gone! I can only assume that the STP filter was the blame. I have now 3,700 miles on this oil change (w/ac filter) and no oil pressure problems. If this is true than I have to question STP's ability to be used in extended drain intervals. W

What do you guys think?? By the way, I am new here and really like the site!

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[Ugly3]

How did the engine run (noises, performance, etc) while the oil pressure was reported to be 100 PSI?

 

[GMBoy]

The engine ran perfectly and with no abnormal noises. I first thought it could be a sender unit, but it has never happened again since I changed the filter back to the AC Delco.

 

[Ugly3]

What I am thinking about is that the oil pump has a releif valve that should limit the pressure to a pre-set value, probably in the 60 PSI range. Even if the oil filter was completly plugged and the bypass in the filter failed to open the oil pressure reported by the guage would not go beyoned the oil pump releif valve limit.

 

[GMBoy]

You are 100% correct in your thinking and that's a real possibity. Maybe it was just a coincidence that it happened with the STP filter. However, it has not happened yet in almost 4k miles. But it could, then I'd have to blame it on the oil pump as you say. I own all the latest GM tools like the Tech 2 and have eliminated any problems in all the electrical areas like body modules, sensors, etc. I hope the problem just does not return. I hate the thought of warranty work and dealership lack-luster repairs

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Thanks for you (fast!) replies.

 

[slalom44]

I have a hunch, and if you still have the old filter I suggest you check it out:

STP filters are made by Champion. Some of these filters have a clicker-type bypass valve. Experience tells me that the bypass valve doesn't work - I had two filters that failed (torn filter media) back-to-back, and I started to burn significantly more oil after that.

If your car's oil pressure sender is located upstream from the filter, then this could result in the high pressure you describe. Many cars have the pressure sender upstream from the filter - for example the 4.0 liter I6 engine used by Chrysler.

Check your STP filter: look down the center tube and if you see a center circle with a bunch of small circles around it on the opposite end, then it has a clicker-type bypass valve.

I don't understand why Champion designed this valve that way because it can't open up with increased pressure - and I have proof. They have recently come out with a new design (E-core) that eliminates this problem.

 

[GMBoy]

I did not know that. (BTW I also own a 2000 Cherokee with the 4.0L what a motor!) Anyway - ironically the pressure sensor for this Aurora is located - get this - right on the oil filter mounting boss! You may be onto something and that may support my "bad filter" theory. Of course, like the other guy mentioned - oil pump relief valve could do it too. But you'd think it would do that all the time - my problem started and stopped at the STP.

 

[94MaxGXE]

I think the clicker type valve sends pulses "shockwaves" through the system that your fancy digital oil pressure monitor reads as high oil pressure.
I know my 96 Acura 1.8 Vtec did not like the Purolator filter with the clicker bypass. The Vtec sys is controlled by oil pressure. That clicker would kick in, and the Vtec sys would not work as expected. Changed to a Wix with a good old fashioned spring bypass, and hold on, feel the difference.

 

[GMBoy]

But why did it not do it until after 3,000 miles is the kicker. But you never know - so far it has not happened again using the trusty AC filter.

 

[Hirev]

The oil pump physically will not put out more oil pressure than normal unless the oil pump bypass got stuck from debris in the oil. The oil pump pressure relief valve is a very close fit (piston to wall) and it will have a cow if it gets debris in it.

Most GM motors including the olds v8 use a Block mounted oil filter pressure relief valve. There is no oil filter pressure relief valve inside the oil filter on this car unless the wrong oil filter was used.