"Oil Service"

ayup.

nate

Nate Nagel wrote in news: snipped-for-privacy@news2.newsguy.com:

Dog ate his Owner's Manual, I figure.

Yes, and most of them are set to come on after a VERY long service interval. So the light actually means your oil should have been changed a couple thousand miles ago.

--scott

No, it means you need to open up the cluster and remove the LED module. Doing this will also add value to your car when you sell it.

I was surprised to learn that the GM oil service lights are activated according to a rather rigidly developed mathematical model. It is not on the basis of any particular "oil quality" sensor. I dont know how Bayerische Motoren Werke does theirs.

I dont trust these lights either, and change my oil when I want to (and that is at

On my old 535, it comes on after 6,000 miles, I believe.

I'd be curious to know what the inputs to GM's model are. Odometer certainly, and maybe integrated fuel consumption. What else?

--scott

Temperature (both engine and ambient) as a function of time, RPM and time spent at given RPM (to detect prolonged idling or crawl-along traffic), probably manifold pressure (which is an indicator of torque and therefore an indicator of main bearing contact prssure), etc. LOTS of information is available to a modern engine management computer.

How does it know you have changed the oil? A microswitch on the drain plug?:-)

Dan

Not a good idea, at least on my old 535i, that would disable the temperature gauge (I know this because the service reminder was flaky on my car, and caused the temp. gauge to be intermittent.)

nate

I think you have to "tell" it. Last time I had a GM rental I remember reading how in the manual, but I've forgotten. Pretty simple, though.

On the 535, you put a meter across two pins of the maintenance connector, then short two other pins with the jumper. When the meter pulses seven times, you remove the jumper and the counter is reset.

You can buy a tool to do this for you in an automated fashion but I am too cheap to do so.

No doubt the GM system will require a proprietary GM workstation to be connected up to the car's ECU...

--scott

In previous years, it could be as simple as pressing a button to reset the system upon fresh oil change.

There were other ways to get to the reset on some models. Probably some scanners could reset as well, but I dont know this for fact.

My Avalon is set up to set the dashlight in accordance with preprogrammed mileage limits.

On my 2000 Silverado, you turn the key without starting the engine and then pump the gas pedal all the way to the floor 3 times. Of course, mine take 5 or 6 pumps but it eventually resets.

Derek

On the Cobalt it's a selection in the DIC...

(Driver Information Center)

As you say, GM's algorithm uses about 5 variables to compute the condition of the motor oil. Makes no difference whether you use synthetic or lowly dinojuice.

I found out that BWM (but I dont know when they started) use a system which is not too different. It is reputedly not just a mileage counter.

Ford apparently is a very simple algorithm which starts you with 5000 miles , and subtracts mileage since last oil change. They also start you with 6 months and subtract the time since your last oil change. Those two values are compared as percentages, and you may be reminded to change at 5000 miles, or six months, etc.

I suspect all these methods are, or have been, in transition.

Uh, yeah, on my 01 Firebird you hold down the trip odo reset until the oil change light flashes. Other GM's have a "reset oil change light" button with the fuse panel.

Ray

On the Chevy full-size vans I've had (all since 2003), all you do is turn the key on, mash the accelerator 3 times, then turn it off. Then it's reset.

Well, I can't think of anything else that Oil Service idiot lights might indicate, so the answer must be yes. Have you read the owners manual recently?