What is measured by the Driver Information Center to determine the percent of oil life remaining?

 

I believe it's an algorythm that's based on engine revolutions and engine temp.

 

 

Also calculated are the number of cold starts and throttle position. Maybe E-T will jump in here and give us the skinny.... he's a retired GM engineer that was involved in the C5 project for those of you unfamiliar of whom I refer.

 

Also ambient air temp,,and trip duration. Short trips = shorter life!!

 

GM OIL LIFE SYSTEM...HOW DOES IT REALLY WORK ?

From the May 2003 GM Techlink publication

How often should engine oil be changed? 3,000 miles, 5,000 miles, 7,500 miles, 10,000 miles? Actually, all of these are correct, depending on operating conditions. Oil life is affected by many factors other than just miles driven. The type of driving, temperature, and engine load all play a part.

That’s why GM has developed the GM Oil Life System, an electronic watchdog that keeps track of all these variables and notifies the driver when it’s time to change oil. This system has become standard equipment on nearly all GM products since 2000.

Briefly, the Oil Life System is programmed with a certain number of engine revolutions. As the engine runs, this number is reduced until it reaches zero, and the Oil Life light or message comes on. But there’s more. Operating the engine under low or high temperatures, and under high load conditions subtracts (penalizes) extra revolutions, so the light comes on sooner. Changing engine oil according to actual need rather than an inflexible schedule provides several benefits. First is simplified determination about when to change oil. No more decisions about normal conditions vs. severe conditions. Second are reduced operating costs for GM’s customers, who now have to change oil only when it’s needed. Third is minimizing the amount of used oil that must be disposed of. And fourth, engines will always be running with sufficiently fresh oil, for long life.

Traditionally, the vehicle maintenance schedule has been based on miles or time, while the oil change interval is now based on the GM Oil Life System.

When the change engine oil light or message comes on, it means that service is required on the vehicle. It should be serviced as soon as possible within the next 600 miles. It is possible that, under the best conditions, the engine oil life system may not indicate that vehicle service is necessary for over a year. However, engine oil and filter must be changed at least once per year, and at this time the system must be reset.

 

I don't believe it takes into consideration the amount of contaminates that could have entered the system, ie., fuel, antifreeze, dirt (dust) and whatever...... I don't know, but I think it probably telling the user, "Change the oil NOW, not in 500 miles".
Like I said, "I don't know", I change mine at 3,000 or as close to that as possible. That way I don't have to worry about it. Waste of money and time? Some people think so, but they're entitled to their opinions.

 

 

I don't believe in those new fangled gadgets. Change oil between 4,000- 7,000 depending on several factors including, more often in the summer and depending how hard the car has been run since last oil change.

 

 

Why do you have fuel and/or antifreeze in your oil?

 

We spent thousands of hours developing the OLM system in order to make it idiot proof.. and like most things... some corvette owners are just a better brand of idiot... we have seen many short cycle, cold start, closed loop trip take the oil life down to 2500 miles... so any idiot who thinks that 3000 or 7000 miles is a good number deserves what they get. these motors have been tested over time using the OLM and were successful in delivering a 200,000 mile motor when using this system.(industry standard for developing a reliable motor is 100,000 miles) we have also seen many many engines fail because of old school thinking. We tried to make this a no brainer and yet people keep telling us they have no brains... When we first started on this system we used a 10,000 mile base line to develop the algorithms, and found that we made it so good that we extended the baseline to 15000 mile in 2000.Every thing is a demerit from the base line.
Car usage is so different.
one guy drives an hour one way thats 2 hours a day @ 1200 rpm highway the motor sees 144,000 revolutions a day X 5 days=720,000 revolutions for a those five days. the car drives 500 miles in those ten hours
2nd car is an around town car, never gets out of 3rd gear and averages 3500 rpm. it takes him two weeks to drive 10 hours or 600 minutes@ 3500 rpm or 2,100,000 revolutions... both cars drive ten hours the second car labors the motor 3 times that of the first and only sees 200 miles.

which car will need an oil change first? Do I have to spell it out any easier?

 

Thanks for the explanation Bill. I definitely use it myself, if anything I'll change it a little early like 5-10% or so. People are just resistant to change, it's the way we're built I guess. Being in IT I see it every day, believe me. It's like the saying goes. We keep engineering around idiots but the universe just builds bigger idiots.

 

Better Idiots...!!!!
Believe me Dave, your 99 has a 10,000 mile base line, you can go all the way to zero and still have a buffer. We designed this system so right that we took the base line to 15000 miles which you could actually calculate to still be safe..we didnt have enough real time data until 2000 to make the change... of course you dont want to exceed one year if that comes first. The PH changes dramatically after a year, due to internal combustion, which for the idiots out there has nothing to do with shelf life, which has been argued.

 

I absolutely believe in the oil life monitor, I always wait for mine to count down to zero before changing the oil and I also like to get my oil analyzed each time as well (it's a fun hobby for me) and each time the report always comes back showing me that my oil still has life left in it and that there are very little wear metals in the oil too, so my engine isn't being hurt one bit by these intervals (typically mine hits zero around 7000 miles). I have even hit zero on the OLM and gone another 2000 miles and the report still looked good! Synthetic oil isn't cheap and it's not going to get any cheaper in the future, so why spend money where it isn't needed? Those of you changing your oil every 3k aren't going to get longer engine life than I am. You might think it's cheap insurance, but I think it's money down the drain for no added benefit whatsoever.

 

I go 5k or one year what ever comes first. If I waited for the DIY it would takes years. Mine only gets 1k/yr.

 

Hahahaha!!!!

 

Learn something new every day !! Thanks for the info ET !! Guess it's time to change the oil.

Thanks Again !!

 

Thanks E-T.
glad to see you have been posting more regularly of late...

 

THanks Rich... it's much easier now than ten years ago, IM too old to fight now.. LOL WAIT!!! No Im not , I just allow alot more rope now... But you know what, there are just as many idiots now as there was back then...there is always someone who thinks they know better because thats what their grandpop did back in the 50's take some of these oil life responses for example... some of these guys think this is their grand pop's 55 Buick Roadmaster that was lucky to see 60,000 miles.
Plus I have to pace myself now.... Mrs Evil can be very demanding.. 43 years of wedded bliss.