CHANGE OIL LIGHT

[GM2500]

I have a 2001 GMC 2500HD with a 6.0 that I purchased a few weeks ago. I changed the oil about 500 miles ago (when I purchased the truck) and yesterday the CHANGE OIL message came up. Is this a programed message that comes up at a set mileage or is it a DP switch that activates it? If it is a set mileage, how do I clear it? Also what are your thoughts on this truck good or bad?

[05Quadrasteer]

To reset the oil life monitor system you have to do the following. Turn the key to the on position, push your accelator to the floor 3 times within 5 seconds. If completed correctly you will see your change oil light flash, or if message is will say the system was reset.

 

As for how long between oil changes there have been many discussions on this forum about when to do it. Or if it is best to just wait until the system tells you to change the oil.

 

Since your last oil change was so recent I would just do the reset of the system and go with what you feel is best. Personally I do mine on a mileage to keep it constant.

 

Have a nice day.

 

Bill

[GM-Tech]

Is this a programed message that comes up at a set mileage or is it a DP switch that activates it? If it is a set mileage, how do I clear it?

 

It has nothing to do with mileage. I have no idea what a "DP" switch is.

 

The oil life monitor is based on engine revolutions and various other factors, but not miles driven. Depending on your driving conditions, the light can come on anywhere from 3,000 miles or less, up to 10,000 miles or more.

[GM2500]

Thanks guys. I was worried that the message was due to a high defential pressure across the filter indicating possible engine damage or problem. I'll try to reset it.

[redvett]

Here is the info on the oil life monitor.

GM OIL LIFE SYSTEM...HOW DOES IT REALLY WORK

This is taken from the May 2003 GM Techlink publication

How often should engine oil be changed? 3,000 miles, 5,000 miles, 7,500 miles, 10,000 miles? Actually, all of these are correct, depending on operating conditions. Oil life is affected by many factors other than just miles driven. The type of driving, temperature, and engine load all play a part.

That’s why GM has developed the GM Oil Life System, an electronic watchdog that keeps track of all these variables and notifies the driver when it’s time to change oil. This system has become standard equipment on nearly all GM products since 2000.

Briefly, the Oil Life System is programmed with a certain number of engine revolutions. As the engine runs, this number is reduced until it reaches zero, and the Oil Life light or message comes on. But there’s more. Operating the engine under low or high temperatures, and under high load conditions subtracts (penalizes) extra revolutions, so the light comes on sooner. Changing engine oil according to actual need rather than an inflexible schedule provides several benefits.

First is simplified determination about when to change oil. No more decisions about normal conditions vs. severe conditions. Second is reduced operating costs for GM’s customers, who now have to change oil only when it’s needed. Third is minimizing the amount of used oil that must be disposed of. And fourth, engines will always be running with sufficiently fresh oil, for long life.

Traditionally, the vehicle maintenance schedule has been based on miles or time, while the oil change interval is now based on the GM Oil Life System.

When the change engine oil light or message comes on, it means that service is required on the vehicle. I should be serviced as soon as possible within the next 600 miles. It is possible that, under the best conditions, the engine oil life system may not indicate that vehicle service is necessary for over a year. However, engine oil and filter must be changed at least once per year, and at this time the system must be reset.

[TonyMazz]

For more information on the basic premise of the invention look up US patent 6.327,900 B1

 

The process it uses is;

 

initialize

V

Determine Engine Oil Temperature

V

Has the oil life been reset

V

IS coolant temperature greater than threshold?

V

Count engine revolutions over a predetermined interval

V

Determine engine oil temperature penalty factor and store in memory

V

Determine contaminant pentalty factor and store in memory

V

multiply temperature and contaminant penalty factors

V

Calculate effective engine revolutions for the predetermined interval

V

Subtract calculated effective revolutions from remaining allowed engine revolutions to create a new value for remaining allowed engine revolutions.

V

Are remaining allowed engine revolutions below a threshold ?

V

If YES activate signal that an engine oil change is needed.

If NO are miles since last oil change above a threshold value ? If yes activate signal that and engine oil change is needed.

 

 

The patent talks about 20,000,000 million revs as a starting point. I have built a spreadsheet that does much of the calculation and of course is very primative since your pcm is reading not only revolutions, but fuel delivery, dynamic temperature of coolant, outside temperature, timing, engine load, time idling, highway, throttle position, and more...

 

It has been determined that the additives in conventional oil ZDDP can deteriorate at a linear rate based on the above conditions. More penalty for short trips, cool engine, high fuel delivery because engine isn't in closed loop could cause more saturation of fuel in crankcase if not brought up to temp and a whole lot more...it's pretty cool.