Oil Life monitor

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From what I have heard, it will adjust depending on your driving style.

If you drive your car like a race car the computer will adjust and the oil life monitor will go down a bit faster.
 
one of the best is in GM vehicles. It counts each revolution of the crankshaft and factors in time, cycles, distance driven, virtually everything relevant.

Some cars it simply counts the miles for you. HUGE differences from car to car. Mercedes actually measures the electrical impedance of the oil.
 
Originally Posted By: stygz
How do oil life monitors work on newer cars?

It varies. Some are based on computer calculations of time, RPM, number of cold starts, amount of fuel consumed, etc. Others have oil sensors that monitor condition of the oil itself.
 
I talked to an Amsoil rep I knew and they did some tests when the OLM said it was about 10% or 15% left. The OLM seemed to him to be fairly acurate.

Just curious how they work.
 
From a GM OLM FAQ:

Quote:


How does the system work?
The GM Oil Life Monitor System is not a mileage counter. It is actually a computer
based software algorithm that determines when to change oil based on engine operating
conditions. There is no actual oil condition sensor. Rather, the computer continuously
monitors engine-operating conditions to determine when to change oil. Over the years,
millions of test miles have been accumulated to calibrate the system for a variety of
vehicles. The system was first introduced in 1988 and is now on more than 10 million
GM vehicles.
 
The GM's OLM works like this. It starts at some maximum value, say 15,000 miles. It basically uses total RPMs to subtract from this value. When you think of it, it makes sense that oil life would depend on total RPMs (wear should also be related to this). Additionally, it uses engine temperature to subtract more value, meaning RPM's while the engine is cold subtract more.

What this does is several things. First, city mileage (where RPMs are higher due to stopping and accelerating) subtract more than highway mileage (where RPMs are lower per mile driven). Secondly, a lot of short trips, where engine doesn't fully warm up, will subtract more.

GM has shown this to be a good system when using UOAs. They even update the program when they learn more through in-service experience. For example, the 1997 Corvette started at 10,000 miles maximum, later they changed it to 15,000 miles. Also GM decreased the maximum on their 3.6 Direct Injection engines.
 
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So the bottom line is what vehicle you have, Mercedes are more sophisticated than my Honda Civic. The Civic OLM ran low way quicker with highway driving than it does with constant short trips that barely warm up the oil. I have a hard time trusting that one. I am sure the Honda engineers are a lot smarter than me but I still change at 50% with the short trips where I used to run it to 15% highway.
 
From a simple mileage counter, to a modified mileage counter [modified from sensory input].
No one that I know of actually tests the oil.
They are geared for dino oil, and synths would go longer.

How well do they work? New ones are decent - a step forwards. In real life, I find that they come out to a small range of mileage for people's individual cars - same as just checking the miles on the oil.
After a while, you know when it's time by either mileage or a light telling you.
 
The fact that GM reprogrammed many of them [for shorter OCIs] in DI engines doesn't leave me all warm and fuzzy. Imaging logging 50K miles or more and then finding out the thing has to be reprogrammed because the OCI was too long? No thanks!
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But really that's no different than accumulating 50K miles on a set OCI that is spec'd too long from the manufacturer, is it? I'm assuming here that something like a sludge prone engine would bennefit from a shorter OCI than originally spec'd.
 
I agree, would you rather GM did NOT correct their mistakes. I know it's better not to make mistakes, but . . .

I think they changed this rather quickly.

Here is why it was done:

I just got a "Customer Satisfaction Program" letter from GM stating that GM's 3.6 liter V6 (the engine used in the Camaro, Saturn Outlook, LaCrosse, Cadillac CTS, and several other cars) is showing premature wear of the timing chain. A quick check of the web turns up that many who own this engine are experiencing troubles all the way up to the engine fragging.



GM is offering to "change the calibration of the engine control module, including the engine oil life monitor, which in most cases will recommed more frequent oil changes".
 
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Originally Posted By: Corvette Owner
I agree, would you rather GM did NOT correct their mistakes. I know it's better not to make mistakes, but . . .

I think they changed this rather quickly.


People followed the OLM like it was Gospel, then defended it when anyone challenged it here. Then GM decided it was not good for DI applications, I wonder how those guys feel having followed it. Granted they corrected it, but how many engines logged some pretty high miles and might have issues as a result? I guess we'll never know, will we? I'd rather do a severe service interval and ignore the OLM, which is exactly what I do with my Jeep, and any vehicle I buy going forward that has an OLM.
 
Originally Posted By: demarpaint
Originally Posted By: Corvette Owner
I agree, would you rather GM did NOT correct their mistakes. I know it's better not to make mistakes, but . . .

I think they changed this rather quickly.


People followed the OLM like it was Gospel, then defended it when anyone challenged it here. Then GM decided it was not good for DI applications, I wonder how those guys feel having followed it. Granted they corrected it, but how many engines logged some pretty high miles and might have issues as a result? I guess we'll never know, will we? I'd rather do a severe service interval and ignore the OLM, which is exactly what I do with my Jeep, and any vehicle I buy going forward that has an OLM.


This is what im doing on my truck. It doesn't give you a percentage I assume a service soon light will light will illuminate in the cluster. I never like olms especially this type. Is rather just keep track myself and not to abruptly fund out in the middle of a trip my oil needs to be changed for example. I just change at 5,000 and call it good
 
This might be an updated version of the article I posted above, although it's still 6 years old...

http://www.motor.com/article.asp?article_ID=994

And some of the info is not exactly correct. For example, most (if not all) current Mercedes vehicles sold in the US are on a fixed 10K mile OCI, so even if the dielectric sensor is there, it is being ignored by the ASSYST.
 
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