Low Oil Pressure Warning! - Any Ideas?

[Northern Ont]

Hey Folks;
First post here, but I bought an '07 Yukon SLT with the 5.3 about 2 months ago, 75 000 km on it, last weekend I was idling in a parking lot when the Low Oil Pressure alarm came on on the dash, with the oil light and a zero indication on the oil pressure gauge. I shut it down, checked the oil - lots there, nothing pissing out the bottom of the engine, went to start it again and nothing. Got a boost and the oil alarm came on again just getting into the driveway.
No strange engine noises or anything (not that you could hear it with the chime ringing in your ear), so I figured that a weak battery screwing with the electrical system may have been the culprit, so I got myself a new battery and installed it earlier this week, and it has been fine until tonight..

When you start it the oil pressure goes up to about 40-50 psi, but then slowly falls until you are at 0. No temperature change on the gauge either.

Anybody have any experience with this problem?

I am suspecting some sort of sensor, what do you guys think?

Up here in Canada we have the 5 yr/160 000 km power train warranty, so I think any issues with the engine or oil pressure should be covered.. Still hate to take it to the dealer...

Thanks for answers or help in advance!
Rob

 

[Northern Ont]

Update

Hey Guys;

So I decided to take it into the dealership, I was fully expecting a malfunctioning sensor, and so was the service manager, so they changed the oil (which I was going to do, but thought they may have to drain it to deal with the possible sensor issue), and then when they put it on the scanner and a data logger they said that the sensor was functioning properly. Service Manager is telling me that a plugged oil filter caused the Low oil pressure indication. I don't believe that for a second, but it's gone 2 days so far with no other issues... Said that it was some sort of crappy filter, but it was on the Yukon when I bought it 2 months ago from them.... Go figure. The oil pressure gauge is a little more active than it was before though. Every change in RPM is reflected in a different oil pressure, which is what is really happening in there...

I'll keep you posted, cause it is intermittent and it went a week the first time without the warning and I fully expect it to be back in short order.

Rob

 

[sumo]

cool thanks for a follow up

 

[OklabyGodhoma]

Your dealer was absolutely right. The good oil filters have a check valve to keep oil in the engine when you shut down and also to supply the sensor with pressure to get a reading. Cheap filters don't put them in....that is why they are cheap. There are only two filters that ever go in any of my vehicles; either WIX or if I know I will be going for long trips or towing I will spend the extra bucks and go with a K&N oil filter.

Sorry but Fram, Mobile 1 oil filters along with no name brands either don't have check valves or poor filter media. I know a lot of people use them but honestly I can't see why. If you have the chance and access to a band saw go to one of the "Quickie Oil Change" places and get a sampling of filters taken out of cars. Cut them in half lengthwise and compare. You will see exactly what I am talking about.

I always run Mobile 1 synthetic in my Yukon XL and normally a WIX oil filter with 10,000 between changes. Have lab tested the removed oil several times with the same results everytime. Run the oil through a 6 micron filter and it can be put right back in the engine. I have other threads about this.

The difference between WIX and K&N oil filters is about $10. The WIX normally around $6 and the K&N around $16. BTW, K&N is used in just about every major NASCAR running today.

You made a big investment.....take care of it!

 

[02Lightning]

What kind of filter was it? I would think it would have a bypass in it if it were to get clogged.

 

[GreatWhite]

Most filters have a check valve, some don't. Most have a bypass, some don't. It has nothing to do with the brand; it's all about what an engine manufacturer specified. If you can get hold of a Fram master catalog you can get all that detail for each part number, and I'm sure that's true for the other manufacturers as well. Of course that means that you can get a "wrong" filter for your application even though the can is the same and it fits. Most filters without bypasses are intended for high-performance applications on the assumption that their owners change filters pretty frequently.

 

[02Lightning]

If that were me I would want it proven to me that the filter was the cause. I would want the filter to cut open and see if it has a blockage inside. Not that I don’t believe there is low standard filters out there (I only use Purolator filters on my cars because of this). I would just want to see it for my self. I would say 9 times out of 10 the filter has some type of bypass in it for this reason. If the filters internals came apart like they say, I would think you could seen filter pieces in the oil when you change it and it could be clogging up your oil pump pick up screen also. If this is all true, I would run your current oil for 500 miles and change it again to make sure all the garbage is out.

 

[Northern Ont]

Update 2

Hey guys;

Thanks for all the ideas. Here's some more background and I did get some info from the service manager...

It was the original oil and filter I got with it when I bought it, I hadn't had a chance to change the oil yet.

Oklahoma - I usually run Mobil 1 Synthetic and Fram filters in my vehicles, but the service manager told me that it was a Purolator Filter that he took off. (As an aside here - I am a Helicopter pilot and the only filters that Bell Helicopters lets you use are Purolator), so Purolator is a very good name in filters... Anyway, he sounded like he had never heard of them, but suggested that I use a Genuine GM filter or a Fram in the future.

Great White - you mentioned that if the correct filter is used, they all should be the same spec (ie. bypass or no bypass...) and I believe that should be true..

I have watched the engineers here at work cut filters open to have a look at metal chips and particles, and all of the media is usually some sort of paper or paper like material. Too bad the dealership probably tossed the old filter.

02 Lightning - I like your idea, We're going to visit some family this weekend so I think I'll change it again next week. That'll be about 1000 k on it, so that should flush everything out.

I'm still pretty skeptical... It is an intermittent problem, so this weekend will tell. Although the oil pressure is definately more responsive than it was before... The other factor is I have no idea how long that oil and filter were on the Yukon before I bought it... Computer said 14% left, but it's math boggles me... I'm going with 5 or 6000 km from now on... I guess I should have changed the oil right off the bat... My bad... It's my first used vehicle...

Anyway, thanks for all the help boys. I'll keep you posted.

Rob

 

[JP East]

Did you ever get to the bottom of this. Was going to buy a 1 owner 08 Yukon SLT that my neighbour traded to the dealership. They ran it through the shop and made it a Optimum used vehicle. Took it for a test and Low oil indicator came on. Took back to shop and they replaced the sensor. Took it out the 2nd time and 10 km's later it happen again. Looking for answer prior to making a decision to purchase or not.

 

[OklabyGodhoma]

Best answer I can give you is to have them change the oil and filter with the brands you want and also ask what their warranty is going to be. If they balk at changing the oil and filter to the brands you specify just ask them one question....."are you going to let an oil change with filter stand in the way of you selling me this car?" If they say yes then run....don't walk for the door and don't look back. They know something is wrong and just want it off the lot. On the other hand if they change it to say Mobil 1 and a good filter like WIX or Purolater and the pressure stays low it is probably just the gauge and your good to go. I would still press for some type of warranty even if its just 60 days or 6000 miles. If there is a problem you will know by then. As always it's a buyer beware world out there. Good Luck.