GM oil life monitor works!

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Oct 4, 2005
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MS
For the longest time I thought this was just a gimmick to let old people know when to change their oil. It always went on at 5k miles after the last change regardless of driving. I started out using dino oil and then switched to M1 synthetic but regardless it would go off at 5k. I switched to GC for my last oil change and to my shock, it went to 6800 miles before it went off. Sure enough, I have already gone past 5k on this oil change with GC. I guess it is just burning less with the GC than it did with the other oils or something.
 
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Mar 5, 2003
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Alberta, Canada
The oil life monitor has nothing to do with the quality of oil in the engine. It goes off based on things like RPM, operating temperature, and many other factors that could potentially degrade the oil. Short trips would cause it to go off sooner than things like all highway miles.
 
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On my '05 GM Opel Astra 1.8 the OLM kicked in at only 4500 miles. Driving style is normal easy driving, no redlines when cold, no really cold starts (have block heater), 80% highway. Dealer had no idea why it went off that early..
 
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Back in Arizona. Finally
My 2005 4.3 Work Truck OLM finally went off at 10,300 miles. I was on pins and needles waiting for that sob to let me change the oil. When the GC came out it was smooth but had endured some fuel dilution (you could smell it). The engine rarely sees over 3500 rpms and is driven in top gear 90% of the time at speeds of 65 - 90 mph. I guess my trek to work is a best case scenario.
 

crw

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Regarding the 1.8l Opel... it might be that smaller engines have different intervals programmed than do the big V8s.
 

vad

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So Cal
quote:
Originally posted by double vanos: When the GC came out it was smooth but had endured some fuel dilution (you could smell it).
Not necessarily. The used oil smells pretty bad in that respect. That's how my used oil samples smell. Yet the UOA showed no fuel dillution.
 
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quote:
Originally posted by crw: Regarding the 1.8l Opel... it might be that smaller engines have different intervals programmed than do the big V8s.
It is. In fact, the GM-OLM is calibrated programmed individually for each particular engine in which it is installed.
 
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quote:
Originally posted by ekpolk:
quote:
Originally posted by crw: Regarding the 1.8l Opel... it might be that smaller engines have different intervals programmed than do the big V8s.
It is. In fact, the GM-OLM is calibrated programmed individually for each particular engine in which it is installed.

And in the Opel 1.8 Ecotec it's 18,000 miles (30 000 km) or 2 yrs, normal service.
 
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bar: It's not just a mileage flag thing. Dig up some of the technical articles on the system. It's pretty intricate, though it does not make any sort of direct measurement of the oil. It combines mileage data with time, rpms, engine temperatures, etc and runs them through its algorithm. This is why there can be so much variation in when the change light comes on (or the numbers count to zero in the numerical version).
 
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That car is driven easy, very, very few redlines, as stated before no really cold starts, mostly highway at 90 km/t (2400 rpm), always more than 40 minutes drives, no towing. I would guess that is very easy for any oil. My cars problem is that the OC warning went on immediately at 7200 km (4500 miles). It's supposed to count down 1500 km before. That didn't happen. Dealer took an oil sample (I asked for it) and reset the OLM/Service indicator to februar 2007.
 
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bar I don't know about your "service indicator", the the OLM is not just a timer you can set to go off on a particular date. Again, the OLM measures a number of data points, and makes a calculation using all that data. It "decides" to turn on the "change oil soon" light (or counts you down to 0% life remaining) based upon this calculation. Respectfully recommend you google the OLM. There are a lot of easy-to-find technical articles on the OLM and how it works.
 
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Levittown, PA
The OLM in my 2005 4.3l Silverado work truck first went off at 18K miles - no kidding! This was 6 months after I bought the truck with 0 mileage, which gives you some idea of the amount of highway driving I was doing. By that time, I had 4 oil changes in the can (I was keen to stay on top of the changes simply for warranty purposes.) Now that the truck is 1K miles away from being out of warranty, I expect to use the OLM for recommended changes with Havoline dino 5W30 unless something doesn't appear quite right. FYI the OLM has only gone off twice in the truck - once at 18K miles, and once at 27K miles. The truck currently has 35K miles on the clock, 13 months after being purchased brand new. One thing to remember - the OLM is calibrated for dino oil at the specifications in the owners manual - not synthetics UNLESS THE OWNERS MANUAL CALLS FOR THEM.
 
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My Colorado OLM first went on at 13K with a mix of city & highway. Oil & filter was first changed to synthetic at 3.5k -- then again with synthetic & new filter at 9K. I completely ignore this system & will now regularly change oil & filter at 7K on odometer. When it comes on again, I will swear at it & reset it. It really peeves me that I had to pay for this OLM that I never wanted.
 
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Jul 23, 2005
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Ontario, Canada
2005 warranty should be just fine with OLM indicated changes. The owners manual in my work 2005 Express van simply says, change the oil when the light comes on, or one year, whichever comes first. I did not find any mileage based quidelines at all in the owners manual. (its olm first came on at 7900km, ~4900miles. Subsequent indications I don't know as the fleet service place keeps resetting the darn thing on me even when I ask them not to). Alex.
 

adjennin

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MS
I guess I just attributed it to the fact that I had changed to a new oil. I had a long trip on the last oil change so maybe that was the reason but my driving habits have not changed.
 

JHZR2

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Dec 14, 2002
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New Jersey
quote:
Originally posted by ekpolk: bar I don't know about your "service indicator", the the OLM is not just a timer you can set to go off on a particular date. Again, the OLM measures a number of data points, and makes a calculation using all that data. It "decides" to turn on the "change oil soon" light (or counts you down to 0% life remaining) based upon this calculation. Respectfully recommend you google the OLM. There are a lot of easy-to-find technical articles on the OLM and how it works.
It is an 'either/or' on the ecotecs in euro cars. My saab 9-3 (saab designed 2.0l turbo with an ecotec block) can tell you the oil condition at any time. It states something to the point of: oil condition 73% 312 days to service. Whichever gets to 0 first is the one you use to change the oil. In talking to a saab engineer, it is a rather complex algorithm to get a percentage (the time to service is just a 2 year countdown). The unit is calibrated to GM LL oil, and uses a lot of inputs. Id venture to guess that the opel variants are set up similarly. JMH
 
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Mizzou-land
Triple_Se7en, I don't want to get personal, but I like data. I like making informed decisions. I don't see the difference in changing at 7K, need it or not, and changing at 3K, need it or not. Are you suggesting that GM's OLM is not performing as well as they say? [Off Topic!] Now the fuel gauge, that is something for which you shouldn't have to pay. You can easily stick a flexible rod down the neck of the tank and accurately determine the amount of fuel left. At cruising speed it may get tough.. [LOL!]
 
Joined
Jul 1, 2005
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Norway
quote:
Originally posted by JHZR2: Id venture to guess that the opel variants are set up similarly.
Yes, The Opel just counts down in kilometer how long to service (the OLM) or the 2 year countdown. That's why I was surprised that it kicked in at 7700 km or 1 year, 2 months. Dealer assumed the timer was set incorrect.
 
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