Should I trust my oil life computer?

[ewynn9]

I change mine at 25%.

As far as I'm concerned, I'll trust a computer and engineers over anyone elses opinion.

[Rocky1974]

Am I the only one that read this?

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.

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.

Let me see if I got this story straight.

GM designs a car and they then put untold dollars and development hours into a system that accurately monitors individual driving conditions and styles to take all the guesswork out of oil changes. Then they engineer a 2:1 safety factor into it and cover the whole thing with a 100,000 mile powertrain warranty. Then people buy the cars and think that they're smarter than GM and their engineers. They say "The hell with all the facts, I'm changing my oil every 3,000 miles."

Well it's your car and your money and you can do what you want, but I think somebody's been watching too many Jiffy Lube commercials.

[denny2188]

I totally agree with Rocky!!!!!! My service manager said with Mobil One, 6,000 miles is good to go between oil changes!!

[HDRDTD]

I normally change the first time around 1,000 miles. From then on, I pay attention to the oil life indicator and usually change it when the oil life left gets down to 40-30 percent.
On my 08 Malibu V6 that works out to around 6-7,000 miles. Same on my 11 Vert.

[NavyDood]

We currently have 7500 miles on the oil in our 2010 SS right now with the OLM showing 48%. This past week I changed the oil filter and added the make up oil. I have ZERO reason to change the oil any sooner than when the OLM gets to 10% or under which should be in the 14K range. Today's oils can very easily go that long. Oil filters on the other hand, especially OEM types are lacking IMO to go that distance. That is why I changed the Delco filter at half way. i will be pulling a oil sample this next oil change and will post up the results when that time comes up.

[kiteman]

there is a guy named patman over on ls1tech that used to run his corvette with different oils and after every 1,000 miles he would send those oils off for tests to see how much they had broken down and worn out.

i don't remember the specific mileage, but i can tell you a good majority of top-tier oils--mobil 1, castrol syntec (german), pennsoil platinum, etc.--lasted well over 10,000 miles without any deterioration whatsoever.

that was the ls1, so i doubt the ls3 would be any different. it still is pretty surprising that people refuse to believe real world oil tests and go by the "3,000/5,000/every 6 months is plenty long for me." that's just an ignorant comment and is absolutely incorrect.

anyway, go to ls1tech.com and search for any post started by patman to see these analyses. here is just one:

http://ls1tech.com/forums/generation...s-gc-0w30.html

[NavyDood]

It's simple kiteman, you can show all the 100% proof and facts that there is and people still think that their "feel good" is a better indicator and has more validity.

[TooCool5]

Originally Posted by David79z28

I change mine at 50% which is around 5000 miles. I am no oil expert. Changing it that often gives me a piece of mind...

Ditto, can't go wrong....

[lbls1]

I change oil at 3,000 miles (dd), or at one quart down (past cars) or at a maximum of 12 months regardless of mileage (stored cars).

I've never had a mechancial breakdown or a blown powertrain due to oil. Additionally, oil that stays in the crankcase longer will be dirtier and have contaminants floating in the oil body, which could contribute to engine wear.

[BigCarrot]

Originally Posted by Krozzbow

well I have 4389 miles on my "Bow". The oil life computes 92% and twice I've had taken it to the dealer for an oil change and said there is no need for it's still good. Still the same oil since Jun'09.

I'd change it after a full year. That is in the owners manual.

It's a sophisticated system. That being said.. I'm waiting till 25% and changing mine.

[ya boy willz]

Originally Posted by David79z28

I change mine at 50% which is around 5000 miles. I am no oil expert. Changing it that often gives me a piece of mind...

Originally Posted by Orange5thGen

Change it and if you are not using synthetic please change to it...

I personally wouldn't ever go more than 6500 miles. The DIC may be very fancy and everything but I'd rather not trust a computer/sensor when it comes to something as crucial as oil. Don't let people tell you to change it at 3k though because that is a total waste. 5k-7k miles would be the sweet spot IMO.

[Codefive]

Just read OP ... funny ... mine comes on before 1000 miles and yours doesnt come on after 9000????

[nyischilly]

Originally Posted by Rocky1974

Am I the only one that read this?



Let me see if I got this story straight.

GM designs a car and they then put untold dollars and development hours into a system that accurately monitors individual driving conditions and styles to take all the guesswork out of oil changes. Then they engineer a 2:1 safety factor into it and cover the whole thing with a 100,000 mile powertrain warranty. Then people buy the cars and think that they're smarter than GM and their engineers. They say "The hell with all the facts, I'm changing my oil every 3,000 miles."

Well it's your car and your money and you can do what you want, but I think somebody's been watching too many Jiffy Lube commercials.

where did you read that from?

[BigCarrot]

Originally Posted by nyischilly

where did you read that from?

http://www.camaro5.com/forums/showthread.php?t=145143

There I'm guessing