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2016 Cadillac CTS-OLM at 60% after 900 hwy miles! #4466288
07/21/17 03:14 PM
07/21/17 03:14 PM
Joined: Nov 2004
Posts: 68
Texas
hal26 Offline OP
hal26  Offline OP

Joined: Nov 2004
Posts: 68
Texas
Bought 2016 2.0 Turbo CTS with 1,036 actual miles and 13 months old. Elderly lady passed away not long after buying the car. Oil Life Monitor was at ZERO. I figured lots of very short trips to the store,doctor etc. I immediately changed the oil/filter myself using Mobil 1 in the proper viscosity. This is now my wife's car and it is her weekend toy. She drives it typically 40 miles a week on the highway and no short trips. Pampered garage queen. I was shocked when the OLM read 60% oil life remaining after only 4 1/2 months and 900 highway miles using top tier premium fuel as well. My wife is 62,drives conservatively,rarely stuck in traffic and little time idling. so the turbo is rarely active and she does not creep around slowly in it - ever. I'm wondering if the OLM would start ticking down to ZERO if the OLM was reset and the car was parked for 12 months (the recommended time between changes)and was not driven a single mile.
Seems like a big waste of expensive oil to change it at around 2,500 miles which is when it will be down to ZERO at the going rate. My question is: Does the OLM use time as one of the major determining factors when calculating oil life?

Last edited by hal26; 07/21/17 03:15 PM.

2016 Dodge Challenger ScatPack 6.4
2003 Harley Road King
2016 Cadillac CTS
2015 Ram Hemi
2016 Triumph 1200 Thruxton
2016 Kawasaki Versys 1000
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466309
07/21/17 03:28 PM
07/21/17 03:28 PM
Joined: Oct 2010
Posts: 1,856
.
Danh Offline
Danh  Offline

Joined: Oct 2010
Posts: 1,856
.
With those two data points is sure looks like the IOLM uses time as one of the factors. Like most OEMs, GM requires an oil change at least once per year, regardless of miles. And 4 1/2 months is about 40% of a year. Given the general cluelessness of the automotive public about such things, it would make sense to include the time element in the IOLM calculations and maybe GM has done so.

It may seem a waste to change oil after only 2,500 miles, but to preserve the warranty it's probably necessary.

If it's an IOLM that counts down in single digits you could take a before/after look if the car was unused for a several days: 4 days should knock the remaining oil life down by a percentage point if time is in the algorithm.

Last edited by Danh; 07/21/17 03:31 PM.
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466313
07/21/17 03:32 PM
07/21/17 03:32 PM
Joined: Jul 2008
Posts: 313
Bucks, PA
zfasts03 Offline
zfasts03  Offline

Joined: Jul 2008
Posts: 313
Bucks, PA
If time has been added to the OLM it is news to me. I know for certain that on 2003 and 2012 GM (Corvette) vehicles time alone does not deplete OLM. Just that the owner manual states if the OLM does not come on in 1 year to change oil and reset.

Possibly time has been added for newer GM vehicles, but this is news to me.

Newer Mercedes Benz vehicles, time does diminish OLM.


03 Corvette Z06
-Amsoil 5w-30 SS
07 Honda Accord 2.4L
-Amsoil 5w-20 SS
16 Suburban 5.3L
-M1 0w-20, XG10575
18 4Runner TRD Off Road
- Amsoil 0w-30 SS, TRD filter
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466316
07/21/17 03:34 PM
07/21/17 03:34 PM
Joined: Jun 2016
Posts: 3,939
MN
oil_film_movies Online content
oil_film_movies  Online Content

Joined: Jun 2016
Posts: 3,939
MN
That is wierd. To answer your question directly, the GM OLM algorithm appears to NOT take into account time.
It does have a maximum miles number in it though.
It basically counts engine revolutions, then penalizes "rough" revolutions (cold, high-RPM, or high load blowby) more.

One more thing: I notice the algorithm immediately orders an oil change if the coolant temperature is way high, no matter what.

Lets take a look at it:

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: zfasts03] #4466325
07/21/17 03:39 PM
07/21/17 03:39 PM
Joined: Jun 2016
Posts: 3,939
MN
oil_film_movies Online content
oil_film_movies  Online Content

Joined: Jun 2016
Posts: 3,939
MN
Originally Posted By: zfasts03
If time has been added to the OLM it is news to me. I know for certain that on 2003 and 2012 GM (Corvette) vehicles time alone does not deplete OLM. Just that the owner manual states if the OLM does not come on in 1 year to change oil and reset.

Possibly time has been added for newer GM vehicles, but this is news to me.

Newer Mercedes Benz vehicles, time does diminish OLM.


I was thinking the same thing. It seems GM could easily add a "max time" to the flow chart shown above. It does seem cars like BMW, Mercedes, mabye Ford's IOLM too, do incorporate a max time.

Related to this, I would like to know the Max Miles allowed, as it does seem to be part of the algorithm reported from https://etda.libraries.psu.edu/files/final_submissions/392
And maybe the max coolant temperature that triggers an immediate oil change light.

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466329
07/21/17 03:41 PM
07/21/17 03:41 PM
Joined: Jul 2008
Posts: 313
Bucks, PA
zfasts03 Offline
zfasts03  Offline

Joined: Jul 2008
Posts: 313
Bucks, PA
It makes sense that time is a factor, but doesn't look like GM takes that into account.


03 Corvette Z06
-Amsoil 5w-30 SS
07 Honda Accord 2.4L
-Amsoil 5w-20 SS
16 Suburban 5.3L
-M1 0w-20, XG10575
18 4Runner TRD Off Road
- Amsoil 0w-30 SS, TRD filter
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466330
07/21/17 03:43 PM
07/21/17 03:43 PM
Joined: May 2012
Posts: 6,157
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline

Joined: May 2012
Posts: 6,157
Fort Lauderdale, FL
Maybe it's one of those engines that lives best when it gets smacked around a little, and it isn't getting that from your wife?


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466351
07/21/17 03:56 PM
07/21/17 03:56 PM
Joined: Jun 2016
Posts: 3,939
MN
oil_film_movies Online content
oil_film_movies  Online Content

Joined: Jun 2016
Posts: 3,939
MN
We can infer, based on the flowchart, how it calculates the percent life remaining.
It is MIN(miles/max_miles,revs/max_revs) expressed as a percent.
(Note the "revs" is really a modified, penalized rev count.)

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466357
07/21/17 04:02 PM
07/21/17 04:02 PM
Joined: Dec 2003
Posts: 10,080
Florida, Cape Coral
Eddie Offline
Eddie  Offline

Joined: Dec 2003
Posts: 10,080
Florida, Cape Coral
Are you sure your wife isn't sneaking off to the drag strip?


CX5 Touring 2.5L :-)
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466374
07/21/17 04:22 PM
07/21/17 04:22 PM
Joined: Apr 2004
Posts: 7,948
New York
pbm Online content
pbm  Online Content

Joined: Apr 2004
Posts: 7,948
New York
The only vehicle I've owned with the GM oil monitoring system was my Chevy Cruze and it definitely DID deplete with time even if not driven....approx. 10% a month. I bet that's what's happening with your Caddy...


'Journalism is Dead'
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466379
07/21/17 04:26 PM
07/21/17 04:26 PM
Joined: Jul 2011
Posts: 1,224
Houston, TX
Coprolite Offline
Coprolite  Offline

Joined: Jul 2011
Posts: 1,224
Houston, TX
My former 2012 F150 EB would run down based upon time or miles. However, if you tore off 3-500 miles after it had sat for a while, it would use the time based deterioration that was previously there. In other words, if you let it sit and lose enough %, the long trip would "mysteriously" not use another % at all. I never got too deeply into it, but time was one boundary and mileage seemed to be the other boundary mathematically. After I confirmed that, I didn't try to see if other factors had any sway in the calculations since I could always do the best case/ worst case comparison when planning OCI.

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466440
07/21/17 05:23 PM
07/21/17 05:23 PM
Joined: Jun 2017
Posts: 395
Western usa
Ammofirst Offline
Ammofirst  Offline

Joined: Jun 2017
Posts: 395
Western usa
No doubt That's seems excessive. Maybe a call to GM is in order to determine if they have in fact introduced a time factor into their olm. We have that engine in our Buick Regal. Every time I change the oil it reeks of gas ⛽️ You seem like a car guy, have you looked into The characteristics of this engine ?

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: hal26] #4466457
07/21/17 05:36 PM
07/21/17 05:36 PM
Joined: Jun 2014
Posts: 2,917
Phoenix, Arizona - USA
SirTanon Online content
SirTanon  Online Content

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Posts: 2,917
Phoenix, Arizona - USA
Any chance it adjusts calculation based on history? If it does, then it may be taking into account that the last owner barely put any miles on it in the previous 13 months, and extrapolating the time/mileage from that into the current fill.


2010 Ford Fusion SE - 2.5 liter/6F35 Trans - 271,000mi
2014 Nissan Altima SL - 2.5 liter/CVT - 62,000mi
Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: SirTanon] #4466462
07/21/17 05:44 PM
07/21/17 05:44 PM
Joined: Jun 2016
Posts: 3,939
MN
oil_film_movies Online content
oil_film_movies  Online Content

Joined: Jun 2016
Posts: 3,939
MN
Originally Posted By: SirTanon
Any chance it adjusts calculation based on history? If it does, then it may be taking into account that the last owner barely put any miles on it in the previous 13 months, and extrapolating the time/mileage from that into the current fill.

That would make sense. It matches what gets recommended to people on bitog all the time. Somebody will write in, say they forgot to change their oil for a long time, and they ask "what should I do?". The advice is often "Run a decent dino oil for 3k miles, change, and then proceed on normal OCI's".

Re: 2016 Cadillac CTS-OLM at 60% after 900 hwy miles! [Re: oil_film_movies] #4466486
07/21/17 06:05 PM
07/21/17 06:05 PM
Joined: Nov 2004
Posts: 68
Texas
hal26 Offline OP
hal26  Offline OP

Joined: Nov 2004
Posts: 68
Texas
Thanks guys for all your helpful insight,much appreciated. I owned 3 C5's and one C6 Vette over an 18 year period and the OLM's never ran down based on time. I averaged about 4K per year in those.
One thing I failed to mention is that we are out in the Central Texas hill country and the weather is mild all year except in the summer when 100 degree temps are not that uncommon. Still 95% highway and no trips or short hops. It has got to be time based.....


2016 Dodge Challenger ScatPack 6.4
2003 Harley Road King
2016 Cadillac CTS
2015 Ram Hemi
2016 Triumph 1200 Thruxton
2016 Kawasaki Versys 1000
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