I'm going to go into this a bit because my new Honda has an OLM similar (I guess) to GMs. It calculates engine factors such as load, revolutions, temps, etc. as well as miles driven and makes assumptions as to oil life expectancy. I read somewhere where it also "penalizes" you for things like short trip driving, thereby reducing the percentage of oil life expectancy.
Most owners of this vehicle (Ridgeline) who have had it long enough to go through a service due notice say that the notice comes on when the oil is at 15%. This seems to occur anywhere between 5,000 and 7,000 miles, depending on driving habits. This contraption is suppose to be so accurate that all service is tied into the monitoring system, even tire rotation notices.
In fact, there is no OCI specified in the manual. It says change oil only when the OLM tells you to or, if you do not drive enough miles for the notice to ever come on, change oil once a year, whichever comes first. There are some notes if I recall about dusty or other "severe" conditions but I'm not certain if those notes applied to the oil (I'm not where I can get my hands on the manual right now).
There are some things the OLM can not know that would impact on OCIs besides "severe" conditions. For example, how does it know if you are using synthetic which should last longer than the dino the OLM is calibrated for? How does it know if you are topping off which will rejuvenate the oil somewhat? Ditto if you are using a product like LC20.
But those factors aside, it seems to me that changing oil (under most normal driving conditions) by this sophisticated software is the best way to go for both protection and conservation, not to mention the money that will be saved as (usually) the OLM extends OCIs beyond the point most people traditionally have gone.
The other option of X number of miles and/or X number of months is old, old thinking and totally arbitrary. I'm not saying that experience should not come into play here as I use to change oil every 5,000 miles no matter what and never had a problem in 40 years of driving cars. But engines have changed and oil has changed, technology has changed, everything has changed! And usually for the better.
I am sold on the OLM concept and I intend to follow it religiously unless I suspect a problem. I know for a fact I'm not as smart about these engines as the Honda engineers that designed and built them so I'll do what they tell me until someone can prove they are wrong.
Having said all this, since this is my first OLM equipped vehicle, I will do periodic UOAs over the years just to be sure this thing is always calibrated and working properly and telling me the truth about my oil and engine.
