How is the oil life calculated by the car? The reason why I ask is I change oil at the end of every season and usually average around 2000 miles per year. This year with about 2000 miles on the car it reads oil life at 13%. It should not be that low. Is there something I am missing.

Thanks,
The Big Dog

 

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-Alex

 

Its more then just miles. I think it calculates by how hard the engine works and stop & starts added w/miles.

 

I'm guessing a few factors would be:

Miles
RPMs
Time spent at a certain RPM
Ambient temp
Oil Temp
How long the engine spends on/off
Air flow or something to monitor the quality of air

Can't think of anymore things that might come unto play right now.

 

I would change it once a year for peace of mind.

 

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 are 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. It 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.

 

those have been the factors quoted in many previous posts on the subject. it is a function of a variety of factors as indicated by the above list plus things like idle time at temp, etc.

 

This will get you started

http://forums.corvetteforum.com/c5-g...-oil-life.html

 

Just out of curiosity, when disconnecting the Neg off the battery for whatever work you have to do on the car, does this affect the oil life monitor or throw it off its last reading in any way?

 

No

 

Maybe you didn't reset the oil life the last time you changed your oil.

 

That's odd, I usually do about 2000 miles a year and last August I had the annual oil changed and state inspection done and I still had 87% of life still on the DIC ?

 

Maybe I missed it, but do you reset the DIC oil usage when you change the oil? It isn't automatic, turn on ignition without starting motor and push accelerator three times, check reading, it should be 100%

 

if anyone knows anything about this subject it is the EVil one.

 

I think that is the case

The Big Dog

 

I just changed the oil in my car (2001 with 34,000 miles), the oil monitor said 87%. I also switched from Castrol to Mobile 1 5w-30. This is the first oil change for me since I just got the car about two months ago. There was a sticker on the windshield from the Castrol oil change that said I had about 3500 miles since the last change.

This is unbelievable to me but the engine is so much quieter I am in shock. It always had a slight rattle at part throttle light load going through the gears which sounded a lot like piston slap, it was at about 2500 to 3000 during light acceleration and not only when it was cold. No noise at all at cruising speed steady state.

That noise is now gone, completely gone. I have been playing with cars for the last 50 years and this is the first time that I could ever hear a difference when I changed oil.

By the way, I will never use Castrol again after this.

 

Thanks for sharing the real-life experience. Your comments have made my mine up I won't be screwing with the "other" oils.

 

Yep, operator error!

 

That's about right.

Maybe the reset button was not hit.

 

Just purchased a '02 Z06 in Oct with 5300 miles on it. The last time the oil was changed was back in 2004 (Mobil 1 5w30). It had travelled approx. 1500 miles on that oil. The DIC indicated 68% oil life and oil was still very clear. Obviously the 1st thing I did was change the oil & filter as well as all other fluids. The car runs like new, do you think there maybe internal engine issues from sitting so long without the oil being changed? There are no leaks from possible hardened gaskets, the under carriage is also bone dry and like new.