The maintenance reminder told me I had about 10% oil life left and it was a warm day in PA on Sunday, so I decided to change the oil. I believe the interval was over 5,000 miles and probably closer to 7,000. Does the RL calculate by mileage or is there a sensor that measures oil dirt and such? I refilled the RL with Mobil 1 and the Fram extended guard filter (though next time I'll probably go with WIX after reading some reviews). The Fram says that it cleans up to 10,000 miles, so I'm wondering if the maintenance reminder will go off based on miles or the status of the oil's dirt. If the filter really cleans that well, I should be able to get a little more life from the oil... Thanks.

 

According to the owner's manual, it's based on engine operating conditions and engine revolutions.

 

Right, in addition, here is some other info from the original 2005 RL introduction, but as you can see, it is an indirect monitoring of the oil; there is no direct inspection of the oil itself to test lubricity and contamination. I am sure there are also certain fixed variables, such as the assumption of the filtering capacity based on a Honda OEM filter, and the recommended API class 5W-20 oil, and not synthetic. I believe the only Acura requiring Mobil One synthetic is the turbocharged RDX.
http://www.hondanews.com/categories/757/releases/2091

MAINTENANCE MINDER SYSTEM

To eliminate unnecessary service stops while ensuring that the vehicle is properly maintained, the RL has a Maintenance Minder System that automatically monitors the vehicle's operating condition. When maintenance is required, the driver is alerted via a message on the Multi-information display.

The system monitors operating conditions such as oil and coolant temperature and engine speed to determine the proper service intervals. Depending on the operating conditions, oil change intervals can be extended to a maximum of 10,000 miles, potentially sparing the owner considerable money and inconvenience over the life of the car. The owner-resettable system monitors all normal service parts and systems, including oil and filter, tire rotation, air-cleaner, automatic transmission fluid, spark plugs, timing belt, coolant, brake pads and more. To prevent driver distraction, maintenance alerts are presented when the ignition is first turned on, not while driving.

 

Basic algorithm based on the above information.....

 

I thought fuel usage was also monitored, but maybe I'm wrong on that....

 

It monitors Brake Pads? Do you know what the threshold is for warning? I know I am getting close to needing new brakes.