I Don't Trust My OLM%

Joined
Dec 15, 2010
Messages
1,027
Location
San Antonio,TX
07 Yukon Denali w/6.2L all aluminum 400 hp engine w/VVT non-AFM. It weighs about 6000 Lb. I drive it easy and it see's mostly hwy miles. Bottom line is "it is hard on oil". It had 157k miles at last oil change. It never needs any make up oil between oil changes. I use nothing but high quality synthetic name brand oil. I do UOA before every oil change and wait to see the results before making the decision to change it or let is go for a little while longer.

Sump capacity was 7 qts for the following:
8100 miles - 25% remaining
6200 miles - 50% remaining
7800 miles - 35% remaining
8600 miles - 25% remaining

UOA results indicate "for me" that the OLM should indicate 0% remaining at 7k miles, or stated another way, 1k miles per each 1 qt of oil sump capacity.

So I added 4 more qts to its sump capacity, an oil cooler, and reduced the thermostat temp from 195* to 185*. Total sump capacity is now 11 qts. I think "now" my OLM will be accurate.

Soon I'll have about 11k miles and 1 yr on the current load of oil(Mobil Delvac 1 ESP 5w30). The OLM will be near 0%. I'll send in a sample for UOA and post the results on BITOG.
 
My wife's Equinox is the only car I've ever had with a olm. I'm not so keen about it's real world ability to say when the oil needs to be changed. It doesn't matter to it, what type or quality of oil you use in the car, it' always says to change it at 5k miles. No matter if you do more highway driving ,or around town stop and go driving. Her car consumes oil, there were times when half the oil was replaced during it's oci, and it has no way to sense that . So in essence it sure seems it's purpose in life is remind the driver when to change the oil . Just a glorified timer.,,
 
My wife's Equinox is the only car I've ever had with a olm. I'm not so keen about it's real world ability to say when the oil needs to be changed. It doesn't matter to it, what type or quality of oil you use in the car, it' always says to change it at 5k miles. No matter if you do more highway driving ,or around town stop and go driving. Her car consumes oil, there were times when half the oil was replaced during it's oci, and it has no way to sense that . So in essence it sure seems it's purpose in life is remind the driver when to change the oil . Just a glorified timer.,,

AGAIN-the only conditions the OLM cannot account for is dusty conditions. Towing a trailer yes, long idle periods yes, etc. You can read this-
The Chevrolet Oil Life Monitor (OLM) system is not a simple oil quality sensor, but a software-based, algorithm-driven device that takes into account various operating conditions of the engine to determine when the oil needs changing. Certain driving habits can affect the life of the oil, as well as driving conditions such as temperature and driving terrain. Lighter, more moderate driving conditions and temperature will require less frequent oil changes and maintenance, while more severe driving conditions will require more frequent oil changes and maintenance. Read the table below to see how the OLM system determines oil life:

The oil life meter is located on the information display on the dashboard, and will count down from 100% oil life to 0% oil life as you continue to drive the vehicle, at which point the computer will trigger a reminder for you to “Change Engine Oil Soon.” Around the 15% oil life threshold, the computer will remind you that an “Oil Change Is Required,” giving you ample time to plan ahead to have your vehicle serviced. It is important not to wait to have your vehicle serviced, especially once the indicator reads 0% oil life. If you do wait and servicing is overdue, you risk severe damage to the engine - which could leave you stranded or worse. GM recommends that an oil change should be completed within two fuel tank fill-ups from when the first message was displayed.
 
CKN, maybe your vehicle works that way, the one in my wife's '11 Equinox does not. It behaves just like I posted earlier. No advance warning for upcoming service, and it doesn't matter to it how the vehicle is used. After each oil change it gets reset to 100%, and counts down to 0 %. At that point it reacts like a timer, and tells you it's time to change the oil. If you changed the oil at 50% life, and refilled it with new oil, I believe it would just continue counting down to 0%, and tell you to change the oil. It's just a timer.,,,
 
Join the club, I've beaten this horse to death. I've ignored both of my OLMs since day one. I followed a severe service interval, got UOAs to confirm I was doing the right thing, and it backed up that following the OLM would have been a mistake. For me an OLM is a useless option forced on me.
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I tested the IOLM on my 2012 3.7L F-150 by deliberately running it down to less than 5% and testing. I used Motorcraft semi-syn and MC filter.

It was highly accurate. But with almost no margin of error. It wasn’t finished. But it was on death’s door.

You don’t have to be BITOG OCD to not want to cut it that close.

Based on my little experiment I don’t mind switching to an IOLM based change interval—-as I said, it was accurate. The only way I’ll get close to running it to zero is if I’m running synthetic. Otherwise more like 25% oil life remaining.
 
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