GM Oil Life Monitor unusual count down

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2006 Chev with a 2.2 litre 4 cylinder ecotec 159,000 miles.
I take note of how the OLM counts down with the miles accumulated and it doesn't make sense to me. In July I went on a 3,500 miles road trip and it counted down faster [per mile] during that highway trip than it does during mixed driving here at home. The highway trip was 65-75 mph cruising for hours on end. Here in the city, the car is used for multiple 5-10 mile trips everyday. I thought steady highway mileage was far easier on the oil but not according to the OLM. Anyone experience this?
 
Originally Posted By: WobblyElvis
Anyone experience this?


No, mine behaves exactly as expected in that regard (highway vs. city i.e. I can go way further between changes on highway miles).

However, there is one condition your car could have been operating in that will penalize the mileage in the GM OLM and that is engine temperature. If your engine was above normal operating temperature on your trip (straining on the highway continuous winds / hills / underpowered etc., AC on, marginal cooling system etc.) then you will rack up a penalty towards the oil change interval. Does your car have a temperature gauge? Was it higher than usual?
 
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The engine temp gauge never moved from normal. The car was fully loaded with 4 passenger and full trunk, but not over loaded. Ac was in use maybe 1/4 of the time and the outside temp was never over 80F. No trailer and not driven hard. The terrain was hilly in some areas but the OLM counted down quickly when cruising flat highways for hours at a time. Just don't get it.
 
Originally Posted By: WobblyElvis
The engine temp gauge never moved from normal. ...


But of course, that doesn't mean that you weren't running at the high-end of the normal range. Maybe that was enough to "penalize" you with the OLM. A code reader or Scanguage can give you more info on the actual coolant temp.
 
The engine turns about 2,400 rpm at 73mph. Gas mileage was good at about 36 mpg. Maybe this is working the engine and oil hard?
 
There has been so much research done with to get the OLM to where it is, do yourself a favor and try not to second guess it. Look to see where you retirement account is in the stock market. Now-that's cause to worry!
 
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Originally Posted By: WobblyElvis
The engine temp gauge never moved from normal. The car was fully loaded with 4 passenger and full trunk, but not over loaded. Ac was in use maybe 1/4 of the time and the outside temp was never over 80F. No trailer and not driven hard. The terrain was hilly in some areas but the OLM counted down quickly when cruising flat highways for hours at a time. Just don't get it.


Well I agree that is strange if the car was functioning fine. I used to own a 2004 Grand Prix when I commuted to a job site daily (180kms one way!) on an out of town assignment. The OLM used to go off at 19,000 kms. Prior to that assignment and after, my normal in town, running around driving would go off at 12,000 kms. Current 2006 GMC, it is always 10k-12k OLM but this vehicle is 90% city 10% highway. My expectation if I took it on a big trip on the freeway would be >12k OLM. I use the OLM exclusively based on these experiences, i.e. it looks about right. In your case I don't know what I would do. Do you think it is possible that 4 people, luggage, pretty good clip on the highway, 2.2L engine that it was running a bit hotter?
 
Originally Posted By: marc1
Originally Posted By: WobblyElvis
The engine temp gauge never moved from normal. The car was fully loaded with 4 passenger and full trunk, but not over loaded. Ac was in use maybe 1/4 of the time and the outside temp was never over 80F. No trailer and not driven hard. The terrain was hilly in some areas but the OLM counted down quickly when cruising flat highways for hours at a time. Just don't get it.


Well I agree that is strange if the car was functioning fine. I used to own a 2004 Grand Prix when I commuted to a job site daily (180kms one way!) on an out of town assignment. The OLM used to go off at 19,000 kms. Prior to that assignment and after, my normal in town, running around driving would go off at 12,000 kms. Current 2006 GMC, it is always 10k-12k OLM but this vehicle is 90% city 10% highway. My expectation if I took it on a big trip on the freeway would be >12k OLM. I use the OLM exclusively based on these experiences, i.e. it looks about right. In your case I don't know what I would do. Do you think it is possible that 4 people, luggage, pretty good clip on the highway, 2.2L engine that it was running a bit hotter?



The driver cannot tell what temperature range the vehicle was operating at. As someone already mention-it probably was in the upper operating range of normal.
 
I doubt very much that the engine was running overly hot in any way. Most of the drive took place at temps between 65-75F and the car has no problems dealing with stop-n-go commuting in 90F heat.

My guess is the OLM surprisingly considers the load [throttle opening] placed on the engine/oil to be a little harsh in this case.

Again conditions were: 65-75mph cruise, 4,100lb loaded car, 2.2 litre engine, ambient temp 65-80F, relatively flat terrain, mid to upper thirties for mileage and little AC use.
 
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Originally Posted By: WobblyElvis
I doubt very much that the engine was running overly hot in any way. ...


Not the point. The OLM has more information than you do. If you suspect the OLM to be in err you'd do well to see all of the information the OLM has at it's disposal. A code reader can get you most of the way there and is a great tool to have around anyway. I've had one of the generic ELM327 ones for several years. It can even read the O2 sensors in my Honda and give me realtime voltage graphs. It was $15. It's a no-brainer buy but check compatibility first with the car(s) you plan to scan.

As an aside, I seem to recall reading about some OLM systems triggering early OCI if the engine RPMs were kept steady for long periods of time. Might be mistaken though.
 
Originally Posted By: B20z
Originally Posted By: WobblyElvis
I doubt very much that the engine was running overly hot in any way. ...


Not the point. .


WobblyE is right, temperature is very much "the point". For sustained RPMs, engine heat gets a little elevated in engines without oil coolers, causing the GM OLM to penalize greater over while counting the high rpms as well.
See https://etda.libraries.psu.edu/paper/9507/5943 for a more complete description of the algorithm used.
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Originally Posted By: B20z
As an aside, I seem to recall reading about some OLM systems triggering early OCI if the engine RPMs were kept steady for long periods of time. Might be mistaken though.

Why do you post? Look up the FACTS, then present them. You do this constantly, spewing junk "seem to recall" jabber.
 
Originally Posted By: ExMachina

WobblyE is right, temperature is very much "the point". For sustained RPMs, engine heat gets a little elevated in engines without oil coolers, causing the GM OLM to penalize greater over while counting the high rpms as well.


I did not say temperature was not the point. On the contrary, temperature is very much the point. What is EXACTLY the point (ignoring your rambling interruption of yet another thread on this fine site) is that the TEMPERATURE GAUGE is NOT an accurate way of judging ENGINE TEMPERATURE. I took the liberty of capitalizing the important bits since your reading comprehension is just so very poor. You need ACCURATE INFORMATION to better judge whether this is or is not an issue.

Originally Posted By: ExMachina

Why do you post? Look up the FACTS, then present them. You do this constantly, spewing junk "seem to recall" jabber.


I offered that info as-is, with a full disclaimer that it may be incorrect. I did that so it could be referenced if the OP wanted to look it up or if any other readers recall something similar. This is how a forum works. I understand all too clearly that qualifying statements is something you're incapable of doing (BTW, are you still waiting for test results on your "double life" filters)? Maybe you want to try a sabbatical to reorient yourself... might I suggest an actual hands-on experience with an engine? It doesn't have the allure of disrupting conversation by reposting slightly altered manufacturer technobabble or anything, but it has it's moments.
 
Again-the OP has no way of knowing what the engine temp was despite his speculation otherwise.

END OF STORY.

This thread is pretty useless without that fact I may add.
 
A different application entirely, but I can confirm this through personal experience.

Being an export vehicle, my GMC calls for an oil meeting ACEA A3-02 spec as bare minimum. The highest I ever got out of an oil change was 18,276 km (11,422 mi) by the time the OLM hit 2%. I have a habit of changing just the oil (drain and refill) at the 50% mark, and changing the oil, filter and air filter when the OLM hits 1-2%.

I have a ScanGauge-II hooked up to my OBD-II port, and I monitor engine coolant temperature and transmission fluid temperature at all times, adjusting my driving habits accordingly. Cylinder head temperature is not been something I've been able to program with the X-Gauges on this application, although I'm able to view that information on my Grand Marquis, and it's usually 2-3 F hotter than coolant temperature.

During the cooler months of the year, when coolant temperature spans from 188 F- 200 F max, I tend to get anywhere between 15,000 km - 18,500 km (9,375 mi - 11,563 mi) between full oil/filter changes based on the OLM. During the hotter times of year, when ambient temperatures hit 140 F and over, my coolant temperatures go all the way up to 224 F at idle regularly. This is ~ 105 C and the idiot gauge remains at the 100 C mark. Whilst average coolant temperature tends to hover around the 206 F mark, 211 F - 215 F at 75 MPH is a regular occurance. This time of year, my average oil/filter interval tends to drop to 12,000 - 13,000 km (7,500 mi - 8,125 mi) mark. The OLM definitely accounts for higher coolant temperatures, even if they are on the upper scale of what is considered "normal".
 
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