How is the engine oil life calculation formulated?

[revrnd]

I didn't know GM had 'capped' the mileage. Like I posted before I did notice that when I got my '04 the OCI had increased. My records went w/ the trucks when I sold them, so I don't have anything to go back on.

 

That all being posted in the thread, have any of you operated a truck in such a way to have 'short' OCIs on the OLS?

[Cowpie]

Well, the time variable must not be a truthful thing.  I changed oil in my 2015 2500 in early June 2016 and didn't change it again for one year and one week later, in mid June 2017.  Put on a little over 2600 miles for the year on the pickup.  OLM still said around 50% when I changed it.   

[KARNUT]

My 06, Trailblazer SS used Mobil 1, the manual said oil changes would come between 12-15K. At mostly HWY miles it never passed 12K. Every time I took it in the sticker they put in the window would say next service in 3K miles. At the miles I drove back then that would be every other wk.


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[redwngr]

The only 'cap' on oil change interval that I've heard of is based on time -- and they didn't program it into the OLM. 

The OM write up says to change a minimum of once per year, even if the OLM is not indicating a change required.

 

 

From the 2018 Sierra/Denali owners manual:

 

"When to Change Engine Oil

This vehicle has a computer system that indicates when to change the engine oil and filter.

This is based on a combination of factors which include engine revolutions, engine temperature, and miles driven.
Based on driving conditions, the mileage at which an oil change is indicated can vary considerably. For the oil life system to work properly, the system must be reset every time the oil is changed.

 

On some vehicles, when the system has calculated that oil life has been diminished, a CHANGE ENGINE OIL SOON message comes on to indicate that an oil change is necessary. Change the oil as soon as possible within the next 1 000 km (600 mi). It is possible that, if driving under the best conditions, the oil life system might indicate that an oil change is not necessary for up to a year. The engine oil and filter must be changed at least once a year and, at this time, the system must be reset. For vehicles without the CHANGE ENGINE OIL SOON message, an oil change is needed when the OIL LIFE REMAINING percentage is near 0%. Your dealer
has trained service people who will perform this work and reset the system. It is also important to check the oil regularly over the course of an oil drain interval and keep it at the proper level.
If the system is ever reset accidentally, the oil must be changed at 5 000 km (3,000 mi) since the last oil change.
Remember to reset the oil life system whenever the oil is changed."

 

 

The duramax supplement info on OLM refers back to the main owners manual.

 

 

 

[RagingRites]

The only 'cap' on oil change interval that I've heard of is based on time -- and they didn't program it into the OLM. 
The OM write up says to change a minimum of once per year, even if the OLM is not indicating a change required.
 
 
From the 2018 Sierra/Denali owners manual:
 
"When to Change Engine Oil

This vehicle has a computer system that indicates when to change the engine oil and filter.
This is based on a combination of factors which include engine revolutions, engine temperature, and miles driven.
Based on driving conditions, the mileage at which an oil change is indicated can vary considerably. For the oil life system to work properly, the system must be reset every time the oil is changed.
 
On some vehicles, when the system has calculated that oil life has been diminished, a CHANGE ENGINE OIL SOON message comes on to indicate that an oil change is necessary. Change the oil as soon as possible within the next 1 000 km (600 mi). It is possible that, if driving under the best conditions, the oil life system might indicate that an oil change is not necessary for up to a year. The engine oil and filter must be changed at least once a year and, at this time, the system must be reset. For vehicles without the CHANGE ENGINE OIL SOON message, an oil change is needed when the OIL LIFE REMAINING percentage is near 0%. Your dealer
has trained service people who will perform this work and reset the system. It is also important to check the oil regularly over the course of an oil drain interval and keep it at the proper level.
If the system is ever reset accidentally, the oil must be changed at 5 000 km (3,000 mi) since the last oil change.
Remember to reset the oil life system whenever the oil is changed."
 
 
The duramax supplement info on OLM refers back to the main owners manual.
 
 
 

What irritates me with the 100%-0% on your oil is if you purchased a maintenance package the percentage drops so much slower cause its set to stretch out to 7,500 miles. If you didn't buy the maintenance package it will run out too zero with 5,000 miles (That is shady business). GM and every other manufacturer will swear on a stack of bibles that isn't true but the General Manager (K.B.) at Freedom Chevrolet Desoto, TX who stated that everyone are trained too say that. It funny cause the oil used in all trucks is a GM Brand Full Synthetic Oil and the oil is rated too run with good a filter 7,500 to 10,000 miles before you need to change the oil, you just may need to check on oil level like everyone should anyways.

I refuse too follow they percentage it lies.

I recently added the Full Synthetic 20k Mobil One Annual Oil in my wifes 2015 Jeep Grand Cherokee Limited 4x4 and its been in the jeep for 6 months 8k in miles without a single problem. I may be putting it into my 2017 Chevy

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[Cowpie]

The idea that OLM will drop to 0 after a full year is a falsehood spread around.  My 2015 2500, I changed oil the first week of June in 2016.  Reset the OLM.  Put about 2700 miles on the pickup in a year.  Changed oil the second week of June 2017.... one week over a year later..... and OLM was at around 60%.   

[Adamrg]

6 hours ago, RagingRites said:

What irritates me with the 100%-0% on your oil is if you purchased a maintenance package the percentage drops so much slower cause its set to stretch out to 7,500 miles. If you didn't buy the maintenance package it will run out too zero with 5,000 miles (That is shady business). GM and every other manufacturer will swear on a stack of bibles that isn't true but the General Manager (K.B.) at Freedom Chevrolet Desoto, TX who stated that everyone are trained too say that. It funny cause the oil used in all trucks is a GM Brand Full Synthetic Oil and the oil is rated too run with good a filter 7,500 to 10,000 miles before you need to change the oil, you just may need to check on oil level like everyone should anyways.
 

That's crazy talk.   

[redwngr]

2 hours ago, Cowpie said:

The idea that OLM will drop to 0 after a full year is a falsehood spread around.  My 2015 2500, I changed oil the first week of June in 2016.  Reset the OLM.  Put about 2700 miles on the pickup in a year.  Changed oil the second week of June 2017.... one week over a year later..... and OLM was at around 60%.   

^^^^^this.

 

Which is why the manual says that regardless of OLM indication, the oil should be changed at least once per year.  

 

 

 

 

[avalonandl]

Just get the oil changed and check the % on the DIC befoe you leave.