Oil sign on at idle, stop, parked.
2007 Hummer H3

Oil sign on at idle, stop, parked.

(2007 Hummer H3)
Hummer H3X oil signal comes on at just about form of the car not moving forward.
I notice that this happens only in the summer time, and the car has been driven for at least 45 minutes. If it's cold there is no oil signal.
I changed the thermostat,oil sensor switch, and I have done a full oil and filter change to no avail.
Car is at 102k miles, Today I was told to use thicker oil (20-W50) in the summer and 10-W30 in winter (NYC).
Not sure what this would do.
4 answers & 5 comments
Popular Answer
on August 04, 2017
Hello,
Any vehicle, regardless of age, make, model, or engine size will have a recommended oil weight (viscosity). This recommendation comes from the manufacturer, and is printed clearly in the owners manual.
This vehicle uses 5W-30, and, like DaveJM said, that is all you should put into it.
Here is how oil works in the engine:
Oil is pumped out of the oil pan by a mechanical pump. It operates on tight clearances, and too thick of oil will cause it to wear more quickly. It will pump the same amount of oil, however.

Once pumped, the oil is sent through oil passages in the engine, just like veins carry blood through the human body.

At the end of oil passages, the oil is pumped into tight spaces between metal components, and allows these components to rotate or rub without making contact. That is the miracle of oil, it allows metal to ride on metal without grinding apart.

When oil is too thick, it causes greater strain on engine bearings and journals (tight clearances) and the oil pump. That will cause a great loss of power.

The other thing to worry about is oil not making it back to the oil pan as quickly as it should. Since there are only a few quarts of oil in the oil pan, thick oil can take too long to trickle back into the oil pan, leaving it at a lower level than normal.
The result is the oil pump sucking in air along with the the oil, and that air will cause metal on metal wear.

Finally, the other aspect to consider is that smaller oil ports will offer greater resistance to oil flow, so the smaller oil ports will not allow sufficient flow of the oil when there are larger oil ports anywhere in the system. This places several components at risk.

Unless the vehicle is operated in the high desert or arctic circle, there is likely no reason to use anything other than what is printed on the oil fill cap and owners manual.

For the oil light:
If it is coming on, an oil pressure test needs to be conducted. Afterwards, the oil pressure sensor signal and reference voltage should be tested.
If the oil pressure tests good, but the signal and reference voltage is incorrect, the engine control module, oil pressure sensor electrical circuit, and the oil pressure sensor should be tested.

AAMCO is suggesting the right thing, and make sure they have an ASE tech on hand who has the scan tool and expertise to test the circuit as well.

They may recommend an engine oil system flush, they may recommend pump replacement, or they may recommend replacing part of the oil pressure sensor circuit or ECM.

Future reference: synthetic oil is better than conventional oil, but will find any leaks you have since it is thinner when not under pressure.

Mixing the two oils is not recommended, but if you are changing the oil it does not matter which it gets filled with.
You can choose to use one, the other, or switch back and forth without cause for concern. This has been shown time and time again.


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on August 04, 2017
Hello,
Any vehicle, regardless of age, make, model, or engine size will have a recommended oil weight (viscosity). This recommendation comes from the manufacturer, and is printed clearly in the owners manual.
This vehicle uses 5W-30, and, like DaveJM said, that is all you should put into it.
Here is how oil works in the engine:
Oil is pumped out of the oil pan by a mechanical pump. It operates on tight clearances, and too thick of oil will cause it to wear more quickly. It will pump the same amount of oil, however.

Once pumped, the oil is sent through oil passages in the engine, just like veins carry blood through the human body.

At the end of oil passages, the oil is pumped into tight spaces between metal components, and allows these components to rotate or rub without making contact. That is the miracle of oil, it allows metal to ride on metal without grinding apart.

When oil is too thick, it causes greater strain on engine bearings and journals (tight clearances) and the oil pump. That will cause a great loss of power.

The other thing to worry about is oil not making it back to the oil pan as quickly as it should. Since there are only a few quarts of oil in the oil pan, thick oil can take too long to trickle back into the oil pan, leaving it at a lower level than normal.
The result is the oil pump sucking in air along with the the oil, and that air will cause metal on metal wear.

Finally, the other aspect to consider is that smaller oil ports will offer greater resistance to oil flow, so the smaller oil ports will not allow sufficient flow of the oil when there are larger oil ports anywhere in the system. This places several components at risk.

Unless the vehicle is operated in the high desert or arctic circle, there is likely no reason to use anything other than what is printed on the oil fill cap and owners manual.

For the oil light:
If it is coming on, an oil pressure test needs to be conducted. Afterwards, the oil pressure sensor signal and reference voltage should be tested.
If the oil pressure tests good, but the signal and reference voltage is incorrect, the engine control module, oil pressure sensor electrical circuit, and the oil pressure sensor should be tested.

AAMCO is suggesting the right thing, and make sure they have an ASE tech on hand who has the scan tool and expertise to test the circuit as well.

They may recommend an engine oil system flush, they may recommend pump replacement, or they may recommend replacing part of the oil pressure sensor circuit or ECM.

Future reference: synthetic oil is better than conventional oil, but will find any leaks you have since it is thinner when not under pressure.

Mixing the two oils is not recommended, but if you are changing the oil it does not matter which it gets filled with.
You can choose to use one, the other, or switch back and forth without cause for concern. This has been shown time and time again.


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on July 31, 2017
Provide proper oil grade for the vehicle, not a 20W50. Good grief. Requires 5W30. 20W50 won't do anything good for you at all.

Have you done a manual oil pressure test? That will tell you a lot. Ensure a fresh oil change with 5W30 is performed first!
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on August 02, 2017
I do out 5w30 which works mostly I the winter. The minute the summer comes this oil signal starts.
many mechanics in NY say that old cars require thicker oil no matter what dealers may say. Not sure why.
I have to drive the car this entire weekend to see if that oil really worked its magic or not.
Nonetheless.
I will ask for a oil pressure.
on August 02, 2017
To give you a sense of what 20W50 will do for you -- nothing good. Engines these days are built with really fine tolerances. They can't tolerate such heavy oil viscosity. You are going to succeed only in just not lubricating various engine components. Although your oil pressure may read higher than previously for a time -- especially at cold starts when the oil cannot get to everywhere it needs to because it's so thick -- you're not doing anything good for your engine.

Back 30+ years ago, you could put 20W50 in an engine that had excessive bearing wear and the thickness would temporarily mask the problem, but these days, it's just bad.
on August 03, 2017
I think I didn't specify a few things.

The car Is originally for 5W30. However a few years ago some mechanic mistakenly put synthetic oil 5W30. When I found this out I was then told I have to out synthetic oil from then on, or mess up the engine.
Fast forward a few years and the car started this oil signal in the summers only.

This last mechanic said to use 20W50 in the summer because there may be some built up in the engine caused by synthetic oil. He said it evaporates and when it does it leaves some sticky stuff residue and that can cause a pressure that is wrong and makes the oil pump send a signal, which is what I see on the dashboard.
So he put this 20W50 and some stuff called LUCAS heavy duty oil stabilizer?
He said it was to clean up any residue.
He also said to put 10W40 in the winter time and to NOT FORGET THIS otherwise there engine will be a problem.

Today, I visited an AAMCO shop and told them what this m chancing did two days ago in terms of engine oil.
AAMCO said that this is really a bad situation. And to change the oil immediately.
So they scheduled me for this Saturday, to out the original 5W30 non synthetic oil.
They added that when the signal comes back on they will then need the car overnight to do a pressure test.

Does this sound like it is really the correct thing to do?

I've already changed oil twice this month and this Saturday will be three times.
I feel like people are taking advantage of me since I do not know crap about this problem.

PLEASE REPLY ASAP.

on August 07, 2017
Ok,
Plainly put: only put engine oil into your engine as specified in your owners manual. Anything else is wrong, speculation, opinion, etc.. Nobody knows the vehicle better than the manufacturer. The manual calls for 5w-30, so use 5w-30.
on August 07, 2017
I called the dealer where I originally bought the hummer H3 back in 2007.
I explained the issue and what was done.
The maintenance department said that old cars work smoother with thicker oil because parts are old.
They said there is no problem with 20-W50 oil in hot weather EXCEPT, if I forget to change to 10-W40 when the weather starts to get cold.
I was asked when I had done this 20-W50 oil change, which was a week ago.
They said to change to 10-W40 in October and leave the car on 10-W40 after that. If I get the oil signal again, once i change the oil, then they recommend do an oil pressure test, since I have already changed the oil sensor and thermostat.
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on August 29, 2018
So one year later the car is doing good. I tried 10W30 but the oil signal returned. I went back to 20W50 and the problem stopped again. Regardless I booked an appointment as you guys suggested even though the oil signal went away and the car is running well for one year.
Appointment is tomorrow 8/30/2018 with a RepaiPal certified shop. Let’s see what they say.
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on September 02, 2018
This extremely strange issue is confusing still, as a super heavy weight oil like 20W50 cannot possibly flow well in an engine that requires lighter weight oil. The only thing I can speculate is that a higher pressure is perceived in the engine because of the heavier weight. That said, extreme risk of damage is possible to components not getting lubrication because of the extreme weight of the oil being used.

All that too say -- I anticipate expensive repairs will be needed to resolve this problem. Or, perhaps the oil pressure switch or circuit could be at fault.

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