GM Oil life monitor-45,000 miles of data

[Benzadmiral]

My V-6 Park Avenue's OLM would usually still be at 40% life left when I'd change at 6 months/4500-5000 miles, so it would drop about 10% a month. However -- and I know it's way too early to tell anything from this -- the OLM in my 4-cyl. non-turbo Regal, driven the same way over the same routes, in chilly but not sub-freezing weather, has dropped 4% in the last week. This suggests 16% a month. At this rate, if hot weather (which'll be here in six weeks) doesn't make any difference, I'll need to change oil in mid-May.

So if it is the same GM OLM, it seems to be coming up with some different answers for different engines, not just being a mileage counter.

 

[PandaBear]

My gut feeling is that some of the short trips all day got cleared / cleaned out by the long 300 miles highway driving in between, because those highway driving boils out the moisture and fuel in the oil and make it fresh again.

Unless your whole OCI is full of short trip vs full of highway driving, you may not see a difference.

 

[hattaresguy]

My truck accounts for ambient temps as well. In the winter I lose 1k-2k miles on the OLM.

 

[RhondaHonda]

Originally Posted By: PandaBear
My gut feeling is that some of the short trips all day got cleared / cleaned out by the long 300 miles highway driving in between, because those highway driving boils out the moisture and fuel in the oil and make it fresh again.

Unless your whole OCI is full of short trip vs full of highway driving, you may not see a difference.


This is certainly a possibility. I only posted this to share my findings. I don't care one way or the other about the oil life monitor as my company specs oil changes and tire rotations at 7500 mile intervals so it doesn't apply to me. I will continue to keep a log of the OLM as it is something that I was curious about, nothing more. I am very surprised at how close it is to 9300 mile OCIs, every time, regardless of ambient temperature, % of highway driving vs. city driving or hours on the oil. The consistency is surprising as I am not a typical driver that drives to work and back 5 days a week and uses the car in about the same manner. Yesterday, for example I drove 93 miles, idled for over 3 hours. Today I will probably drive 8 miles and that is it.

 

[Coprolite]

Try keeping track of each % drop during one OCI. This will let you analyze the micro-behavior of your OLM. My EcoBoost IOLM will drop upon start up after a few days(time based, likely 365 days = 100%) and has a mileage cap at 100 miles/% unless the long driving occurs immediately after a time based drop. This seems to "claw back" some of the time based loss. Time to warm up also has an impact. During the cold, it will lose life faster due to slower warm up. Of course, Houston weather and a long commute after my last relocation made this a lot more boring, since it now pegs out at 100 miles most of the time.

If I were to try to examine the behavior by comparing OCIs, I would not see much variation at all. This is mainly due to the fact that we split our driving between two cars and probably average 1.3 oil changes a year.

 

[steve20]

From observing our cars with GM OLMs I can tell you highway driving is approx 1% per 100 miles = 10K miles OCI.
Our 04 Tahoe has routinely made 'straight-thru' trips from NJ to FL 1250 miles takes about 17 hours. When we arrive it used 12% of oil life. Same thing on the FL to NJ leg of the trip another 12% gone. In either direction, it is straight thru driving with stops only for gas, and obviously only 1 warmup. My conclusion is, when you add all of your driving together over 7 K miles----it all evens out, and you are getting almost optiumal OCIs