Engine Oil Life % on dash readout
09-24-2009, 10:23 AM
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Engine Oil Life % on dash readout
Its been a little over 3 months since my last oil change, yet the engine oil life is still reading around 60%. Used conventional 5w-30 as usual, and reset the oil life readout when it was last changed.
Should i trust this, or just go ahead and change it????
Should i trust this, or just go ahead and change it????
09-24-2009, 12:54 PM
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The GM OLM System does not go by miles traveled. IIRC it is based on several different variables such as; engine temps, rpms, etc. My manual says to change when the "Change Engine Oil" light comes on or at least once a year, which ever comes first.
I changed my oil on 1/31/09 and have put almost exactly 3,000 miles on it since then and I still have about 40% left on the OLM, so if my driving style doesn't change between now and then it looks like I'll be changing it due to the "at least once a year" requirement instead of the OLM.
But to put your mind at ease, spend $22.50 and send your oil off for analysis to http://www.blackstone-labs.com. If you do send it off for analysis let us know your results.
I changed my oil on 1/31/09 and have put almost exactly 3,000 miles on it since then and I still have about 40% left on the OLM, so if my driving style doesn't change between now and then it looks like I'll be changing it due to the "at least once a year" requirement instead of the OLM.
But to put your mind at ease, spend $22.50 and send your oil off for analysis to http://www.blackstone-labs.com. If you do send it off for analysis let us know your results.
09-29-2009, 08:10 PM
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From bobistheoilgut.com
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.
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 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.
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.
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09-30-2009, 08:08 AM
#8
I followed the OLM once...never again! I went 9000 miles on the oil and it was sludge when it came out. I have since reverted to my old ways...start at a 5K change, still black, so I backed 5oo miles for every following change until I hit 2500 and the oil wasn't black, so I bumped it back to 3000 between changes. Might be a little more expensive, but it works.
09-30-2009, 08:46 AM
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I change my oil every 5000 miles because I strictly use Mobil 1 Full Synthetic. But, the GM OLS was developed for a reason. It takes in a multitude of diffrent values ranging from Combustion Events, Ignition Events, Engine Temp and so on. I don't strictly follow the OLS messenger either, but it is there to keep you from wasting your money. If you put 3000 miles on your car in just one or two hoghway trips, odds are your oil is still good and the viscosity hasn't broken down yet. But 3000 miles on 40 diffrent short trips and long idle times will break it down quicker. So in essence it's actually a good thing. But with the advance of today's oils and lubricants, 3000 is almost over changing it sometimes. I advise checking your oil every 1000 miles, and keep a log of the condition and usage. At 3000, if it looks bad, or has some consumption, then go ahead and change it. If it still looks good, then put another 1000 miles on it and check it. But to each his own.
Here's a handy little snipit:
GM Oil Life System Resetting
When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL SOON message will come on. Change the engine oil as soon as possible within the next 1 000 km (600 miles). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset.
If the system is ever reset accidentally, change the engine oil at 5 000 km (3,000 miles) since last oil change.
How to Reset the Engine Oil Life System
The Engine Oil Life System calculates when to change the engine oil and filter based on vehicle use. Anytime the oil is changed, reset the system so it can calculate when the next oil change is required. If a situation occurs where the oil is changed prior to a CHANGE ENGINE OIL SOON message being turned on, reset the system.
If the vehicle does not have a Driver Information Center (DIC), do the following:
Turn the ignition to ON, with the engine OFF.
Fully press and release the accelerator pedal slowly three times within five seconds.
Turn the key to OFF. If the CHANGE ENGINE OIL SOON message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure.
If the vehicle has a DIC, do the following:
Turn the ignition to ON, with the engine OFF.
Press the MODE button until the DIC reads OIL LIFE LEFT/HOLD SET TO RESET.
Press and hold the SET button until 100 percent is displayed. You will hear three chimes and the CHANGE ENGINE OIL SOON message will go off.
Turn the key to OFF.
If the CHANGE ENGINE OIL SOON message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure.
Here's a handy little snipit:
GM Oil Life System Resetting
When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL SOON message will come on. Change the engine oil as soon as possible within the next 1 000 km (600 miles). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset.
If the system is ever reset accidentally, change the engine oil at 5 000 km (3,000 miles) since last oil change.
How to Reset the Engine Oil Life System
The Engine Oil Life System calculates when to change the engine oil and filter based on vehicle use. Anytime the oil is changed, reset the system so it can calculate when the next oil change is required. If a situation occurs where the oil is changed prior to a CHANGE ENGINE OIL SOON message being turned on, reset the system.
If the vehicle does not have a Driver Information Center (DIC), do the following:
Turn the ignition to ON, with the engine OFF.
Fully press and release the accelerator pedal slowly three times within five seconds.
Turn the key to OFF. If the CHANGE ENGINE OIL SOON message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure.
If the vehicle has a DIC, do the following:
Turn the ignition to ON, with the engine OFF.
Press the MODE button until the DIC reads OIL LIFE LEFT/HOLD SET TO RESET.
Press and hold the SET button until 100 percent is displayed. You will hear three chimes and the CHANGE ENGINE OIL SOON message will go off.
Turn the key to OFF.
If the CHANGE ENGINE OIL SOON message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure.
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