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2008-2013 Cadillac CTS General Discussion Discussion, Oil Life Monitor Question in Cadillac CTS Second Generation Forum - 2008-2013; Originally Posted by louiefl99 Anyone else out there with a 2011 Coupe or Sedan care to post their mileage and ...
  1. #16
    rayle is offline Cadillac Owners Fanatic
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    Re: Oil Life Monitor Question

    Quote Originally Posted by louiefl99
    Anyone else out there with a 2011 Coupe or Sedan care to post their mileage and % oil life?
    2011 Coupe AWD
    Mileage = 960
    % oil life = 87%

  2. #17
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    spind is offline Cadillac Owners Fanatic
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    2011 coupe 3.6 awd
    2400km olm @80%
    changed oil & reset olm to remove beak-in contaminants (not required by GM and not covered under maintainence pln, but I feel it is $66 well spent)

  3. #18
    Joe
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    Re: Oil Life Monitor Question

    I'm not as trusting of these sensors as the rest of you. Fuel dilution will slowly destroy this engine by reduced lubrication to critical components. I'll stay with my common sense. If it looks dirty, feels dirty, smells dirty and its been around 5000 miles since the last oil change, its due. It's cheap insurance to change the oil and not worry about saving a few bucks. Happy Motoring!

  4. #19
    TrimThis is offline Cadillac Owners Fanatic
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    Re: Oil Life Monitor Question

    Why am I thinking that when Caddy went to free maintenance the mileage when up.

  5. #20
    RippyPartsDept's Avatar
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    Re: Oil Life Monitor Question

    Whenever this topic comes up I get the urge and feel the need to repost this (note that what i'm reposting is actually a repost itself)

    Quote Originally Posted by Ranger View Post
    Yes it is very accutrate. Here is how our old guru explained it.
    "One thing I can touch on and clear up.....the GM oil life monitor operation and my statement that ZDP (or ZDDP as you tend to call it here...most of the API literature just sticks to ZDP so I tend to use that) depletion is the basis for oil deterioration.

    My spelling is poor but ZDP stands for zinc dialkyldithiophosphate which , as it sounds, is an anti-wear compound comprised of zinc and phosphorus.

    ZDP is dispersed in the oil so as to be at a potential wear site if a surface asperity happens to break thru the oil film thickness causing the dreaded metal-to-metal contact. A molecule of ZDP must be present at that moment to prevent microwelding at the contact site which will cause material transfer, scuffing, scoring, wear and catostrophic failure. The concentration of ZDP in the oil will determine if there is ZDP present to work it's magic. The greater the concentration...the more likely a molecule of ZDP will be there...and vice versa.

    By nature, ZDP is sacrifical. As ZDP is "used up" at a wear site to prevent micorwelding the concentration of ZDP decreases.... So...if you measure the ZDP concentration in engine oil in a running engine it will decrease at linear rate based on engine revolutions. Any given engine has a certain number of high potential wear areas where metal-to-metal contact could occur due to reduced film thickness and/or surface asperities....areas such as rubbing element cam followers, distributor gears, rocker arm pivots, push rod tips, etc...... The more of these areas the more ZDP depletion. The more often these features come in contact the greater the ZDP depletion. That is why, generally speaking, ZDP concentration in the oil, for any given engine, will decrease at a fairly linear rate when plotted versus cummulative engine revolutions. The more times it turns the more contact the more chance for wear the greater the depletion. This is as much of a fact as I could quote ever and is really not speculation or anything. It is proven beyond a shadow of a doubt in many studies. That is why it is ONE of the basis for determining oil life remaining and why it is THE basic premis of the GM oil life algorithm. It is only ONE of the things that determines oil life...but it is the one thing that can be tied to engine operation in a linear fashion and estimated very accurately by accumulating engine revolutions via a counter.

    The GM engine oil life monitor counts engine revolutions and accumulates the number for the basis of the oil life calculation. It then adds deterioration factors for operating temperature, start up temperature, soak times, ambient, coolant temperature, etc... There are a LOT of factors that "adjust" or affect the slope of the deterioration but the fundamental deterioration is traced back to the ZDP depletion that is inescapable with engine revolutions. The specific rate of ZDP depletion is readily measurable for any given engine so that is the fundamental item that is first calibrated for the oil life algorithm to tailor it specifically to that engine. <<<< does that paragraph get anyone else excited besides me? laugh.gif

    You would obviously like to get the oil out of the engine before the ZDP concentration gets so low that it is ineffective at being at the right place at the right time and preventing engine wear so that becomes the long term limit on oil life for that application.

    The other things that determine oil life such a acid build up, oxidation, petane insuluables such as silicon from dust/dirt, carbon or soot build up from the EGR in blowby, water contamination, fuel contamination, etc.... are all modeled by the multipliers or deterioration factors that "adjust" the immediate slope of the line defined by the engine revolution counter as those items can be modeled in other ways and accounted for in the immediate slope of the ZDP depletion line.

    The algorithm was developed over the course of many years by several lubrication experts at GM Fuels and Lubes, spearheaded by Doctor Shirley Schwartz who holds the patents (with GM) for the algorithm and the oil life montitor. I had the luck of working directly with Dr. Schwartz when the idea of the oil life monitor first progressed from the theoretical/lab stage to real world testing/development/validation. There were fleets of cars operated under all conditions that deteriorate the oil life for any and every reason and , thru oil sampling and detailed analysis of the oil condition, the algorithm was developed, fine tuned and validated to be the most accurate way invented yet to recommend an oil change interval by. As just one example, I have seen cars driven side-by-side on trips, one towing a trailer and one not, for instance, to prove the effectiveness of the oil life monitor in deteriorating the oil at a faster rate just because of the higher load, higher average RPM, higher temps, etc...and it works flawlessly.

    The oil life monitor is so effective because: it is customized for that specific vehicle/engine, it takes everything into account that deteriorates the oil, it is ALWAYS working so as to take into account THAT INDIVIDUALS driving schedule, and it tailors the oil change to that schedule and predicts, on an ongoing basis, the oil life remaining so that that specific individual can plan an oil change accordingly. No other system can do this that effectively.

    One thing is that I know personally from years of testing and thousands of oil analysis that the oil life algorithm works. There is simply no argument to the contrary. If you don't believe me, fine, but, trust me, it works. It is accurate because it has been calibrated for each specific engine it is installed on and there is considerable testing and validation of the oil life monitor on that specific application. NOt something that oil companies or Amsoil do. They generalize....the oil life monitor is very specific for that application.

    Oil condition sensors in some BMW and Mercedes products are useful, also. They have their limitations, though, as they can be blind to some contaminates and can, themselves, be contaminated by certain markers or constituents of certain engine oils. Oil condition sensors can only react to the specific oil at that moment and they add complexity, cost and another potential item to fail. One other beauty of the GM oil life monitor is that it is all software and does not add any mechanical complexity, mass, wiring or potential failure mechanism.

    There is considerable safety factor in the GM oil life monitor. Typically, I would say, there is a 2:1 safety factor in the slope of the ZDP depletion curve....in other words, zero percent oil life per the ZDP depletion is not zero ZDP but twice the concentration of ZDP considered critical for THAT engine to operate under all conditions reliably with no wear. This is always a subject of discussion as to just how low do you want the ZDP to get before the oil is "worn out" if this is the deciding factor for oil life. We would tend to be on the conservative side. If the oil life is counting down on a slope that would recommend a 10K change interval then there is probably 20K oil life before the ZDP is catostrophically depleted....not that you would want to go there...but reason why many people are successful in running those change intervals.

    Please...NOT ALL ENGINES ARE THE SAME. The example above is an excellent practical justification of why you would want to add EOS and change the 15W40 Delvac in the muscle car at 3000 miles max and yet can run the Northstar to 12500 easily on conventional oil. You must treat each engine and situation differently and what applies to one does not retroactively apply to others. This is where Amsoil falls short in my book by proposing long change intervals in most everything if you use their oil. It just doesn't work that way. You can run the Amsoil to 12500 with no concerns whatsoever in the late model Northstar because even the oil life monitor tells you that for conventional oil off the shelf. Would I do that to the 502 in my 66 Chevelle...NO WAY. Amsoil says I can though. Wrong.


    There are entire SAE papers written on the GM oil life monitor and one could write a book on it so it is hard to touch on all aspects of it in a single post. Hopefully we hit the high spots. Realize that a GREAT deal of time, work and energy went into developing the oil life monitor and it has received acclaim from engineering organizations, petroleum organizations, environmental groups all across the board. It is not some widget invented in a week and tacked onto the car.

    The oil life monitor is not under the control of a summer intern at GM Powertrain per an earlier post....LOL Not that a summer intern wasn't compiling calibrations or doing a project on it but is under control of the lube group with a variety of engineers directly responsible that have immediate responsibility for the different engine families and engine groups. The idea that a summer intern was responsible for or handling the oil life monitor is ludicrous.....LOL LOL LOL"
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  6. #21
    928S is offline Cadillac Owners Connoisseur
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    Re: Oil Life Monitor Question

    Quote Originally Posted by RippyPartsDept View Post
    Originally Posted by Ranger (where, when?)

    The oil life monitor is not under the control of a summer intern at GM Powertrain per an earlier post....LOL Not that a summer intern wasn't compiling calibrations or doing a project on it but is under control of the lube group with a variety of engineers directly responsible that have immediate responsibility for the different engine families and engine groups. The idea that a summer intern was responsible for or handling the oil life monitor is ludicrous.....LOL LOL LOL
    Not ludicrous at all. Regarding the OLM (recalled, recalibrated...duh!) GM has no credibility, in my opinion. According to OLM, my 3.6L DI oil life recommended oil change interval was ~13Kmi before recall and now ~5.8Kmi. (-55%) after recall. That's not fine-tuning, it's repudiation of the OLM that "Ranger" defends.

  7. #22
    RippyPartsDept's Avatar
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    Re: Oil Life Monitor Question

    you're talking about just a couple year models that had the 're-calibration' done to them... the OLM has been in use since at least the early '90s and this is the first time there's ever been a 're-calibration' recall

    just a day or two ago there was another forum member who mentioned that the 're-calibration' barely changed their oil change interval and they were surprised

    the OLM is scientifically proven ... once change in the OLM in one engine in all it's time in use... very credible
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  8. #23
    928S is offline Cadillac Owners Connoisseur
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    Re: Oil Life Monitor Question

    Hundreds of thousands of vehicles, three model years. The OLM counted short-trip, stop-n-go, temperature extreme, city driving essentially the same as long-distance, sustained-temperature/rpm/mph highway driving. That's indefensible, in my opinion, but nothing new for GM.

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  9. #24
    JimmyH is offline Cadillac Owners 10000+ Posts
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    Re: Oil Life Monitor Question

    Then don't use it. Pretty simple.

  10. #25
    RippyPartsDept's Avatar
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    Re: Oil Life Monitor Question

    all those vehicles have the same engine...
    the OLM has been in use since 1984 !!!
    how many other millions of cars have used the system without ever needing a 'recalibration' ??

    sure, it's unfortunate that there was something wrong with the use of the OLM in this one instance, but you can't say that the system is not reliable
    and whatever it was that was wrong with the application of the OLM in this instance was probably not the fault of the OLM, but the engine design itself
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  11. #26
    928S is offline Cadillac Owners Connoisseur
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    Re: Oil Life Monitor Question

    So it was faulty engine design that made my OLM, and presumably others, erroneously score short-trip, stop-n-go, temperature extreme, city driving essentially the same as long-distance, sustained-temperature/rpm/mph highway driving? I think not. I would agree that both 3.6L engine design and OLM were deficient.

    BTW...on the day that I took delivery back in Dec 2007, my salesman introduced me to the dealership Service Manager. He urged me upfront to disregard the OLM and get motor oil changed every six months at minimum, but skeptic I chose to follow the Owner’s Manual/OLM instead. In retrospect, it seems that problems were known by insiders long before GM decided to take corrective action.

  12. #27
    RippyPartsDept's Avatar
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    Re: Oil Life Monitor Question

    i don't know exactly what it was, but that engine is the only one that's ever had a problem since 1984... so ... almost 30 years of scientifically proven oil life calculations

    like jimmy said, you can choose to ignore it - just don't presume you or your service manager know better than the oil/lube scientists at GM - i don't
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  13. #28
    Richard MacGregor is offline Cadillac Owners Fanatic
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    Re: Oil Life Monitor Question

    redvette was the best poster in this thread! Anything else besides oil analysis is just guesswork or hearsay. Short of doing this test using the brand oil you intend to use, you can't be 100% sure.

    Richard

  14. #29
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    Re: Oil Life Monitor Question

    I think all this discussion is based on speculation. I have never been condition to do 3,000 miles oil change. I simply do not believe it. I have driven many cars that the manufacturers suggested change interval at 6,000 or more miles. Never had any problems!
    OLM – did some research and it seems that the fundamentals are sound. What happened was somebody in GM screwed up in a big way in the CTS application so many of us have now doubts as to the OLM reliability.
    Last weekend I have changed oil after a bit over 5,000 miles. The OLM was still showing 50% remaining oil life left. Why did I change? The oil level was starting to be on a low side and I would need to add a quart soon. Also, given the history with timing chains and OLM I wanted to be on a safe site. I did take an oil sample and sent it to the lab for analysis. It will be interesting to see how it compares with the OLM.

    BTW. We have some very vocal GM employees on this forum. They accused some of us of taking advantage of GM etc. Where are you now that we need some real information? And to be honest yes, your management screwed the company and we, the tax payers had to bail you out.

  15. #30
    JimmyH is offline Cadillac Owners 10000+ Posts
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    Re: Oil Life Monitor Question

    this discussion is about the oil life monitor. let's it keep that it way please.

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