As some of you may know I have a '05 quad cab 4x4 colorado. They have this system programed in the computer that is supposed to tell you when to change the oil. It calculates engine rotations and RPM's to determine the trucks level of usage. I think it's just nuts!

The manual even says that under light use the truck may not even tell you to change the oil for a year! Out of pure morbid cusiousity I decided to give it a try and see when it would tell us to change the oil. So I changed the oil, reset the system per manual instructions and gave it a shot.

My wife drives it mainly so it was somewhat easy to ignore. 3000 miles passed, 5000 miles passed, 8000 miles passed and now I was starting to wonder. My civic manual stated to change the oil every 10,000 miles and the filter every 20,000 miles. I still did my usual 5000 mile synthetic oil blend and filter change on that car anyway but seeing this before made me realize that it was possible to go this long. Where it started getting difficult was when we passed 10,000 miles.

Now it was getting hard waiting for that damn change oil message. I was sure it was busted but I held out longer. At 12,000 miles I broke down(personally) and changed the oil. I just couldn't take it anymore.

After 12,000 miles when I changed the oil I did not reset the oil change system and it took another 3000 miles for it to finally tell me to change the oil. That system waited 15,000 miles before it thought it worked enough for an oil change.

To me this seems like a nutty system but I also know that some engineer that designed the system might know better then I do. Would any of you had waited 15,000 miles for the system to tell you to change the oil? I know I couldn't wait that long and I don't ever plan on waiting half as long again.

 

Herein lies the possible problem with what you have. The computer really can't tell if these were highway miles or severe towing on a hilly, dusty road.
As you found out, it can't distinguish between old oil and clean oil that you have after you did an oil change. It just guesses.
Really about the only good this indicator would be helpful is an owner who just drives and drives and drives without paying attention to mileage and doesn't have a clue when to service a vehicle.
My first vehicle that had anything similar to this was an '88 Cougar with the digital dash. About every 8K miles the service engine light came on. At least it was simple to reset. A lot of Dodge service engine reminder lights are a PITA to reset.

 

Nope, I would change oil and filter around 3,000 - 3,500 miles as always. I would ask the service department how to disable the device at my earliest convenience.

 

this is a perfect example of the fact that most gm drivers need a light to tell them it is time to service their vehicle.
ford drivers don't need no stinking light. we KNOW that you change your oil every 3,000 miles.

 

the device can not be dissabled. it is a very well thought out system. it takes into account more than just engine rpm and distance. i bet if you did a uoa on that oil which was in there 12k it would have been fine. try a google search on the gm oil life monitor

 

The book actually says it has nothing to do with distance. It might have been fine but some things are hard to trust when you aren't used to them. I'll stick to the 5k oil changes from now on, 3k is just overkill with what I put in it. I had a feeling I wouldn't be alone with this one, thanks for the input.

 

This argument re oil change intervals will never be settled. I agree with those that say changing at 3000 miles is just throwing away good oil. Here's something interesting from Consumer Reports:
Consumer Reports, with one of the most widely respected product testing laboratories in the world has just released the results of an extensive test on oil brands and oil changes, as well as other issues regarding car care. In the process, the test demolished much of the conventional wisdom regarding car lubrication. The two most surprising results: the frequency with which oil is changed doesn't matter after the first few oil changes on a new engine, and the type or brand of oil used can not be shown to make any difference.

The testers placed freshly rebuilt engines in 75 New York taxis and then ran them for nearly two years, with each cab racking up 60,000 miles, placing different brands and weights in different cars and changing the oil at 3,000 miles in half the cars and 6,000 in the other half. At the conclusion of the test period, the engines were torn down, measured and inspected. The conclusions: Regardless of brand of oil or weight, no measurable differences could be observed in engine wear. Furthermore, there was no difference among cars which had oil changed at the shorter or longer interval.

Dono

 

Interesting stuff. There's more to this than meets the eye.

"After many years of research, GM has learned how to maximize oil drain intervals while also maintaining engine life. Researchers learned that oil degrades in a predictable fashion and that monitoring a few engine-operating conditions allows oil life to be determined quite accurately. Specifically, the engine computer monitors engine speed to count combustion events while also estimating oil temperature based other engine operating conditions. From here, the computer is able to determine the rate of oil deterioration and notifies when to change oil. This software based GM Oil Life System is part of the same computer that also helps to control engine functions and is now available on most GM vehicles. With this system, the guesswork of knowing when to change oil is removed."

 

I couldn't agree more. This is one of those things that a person should just do what ever makes them feel warm and fuzzy inside. It's like the blend debate. I personally have seen dramatic increases in engine life in off-road racing using blends. Cylinders & vavle trains lasting longer and bearings just looking great in the long run. I have faith in using blends for 5k intervals in my autos and couldn't care less what people have to say about it. It's just like the GM oil system, I'm sure it works fine but it doesn't make me feel "warm and fuzzy" inside.

 

Thats interesting.

 

I don't have much experience yet with newer cars. (My first car and first love was a 1969 Ford Falcon) I changed the oil in my Falcon every 3,000 miles and by that time it was goop. With all of the newer vehicles in my family, 95 GMC minivan, 97 GMC 1500, 02 Ford Ranger, we run AMSOIL, a synthetic that you change ever 25,000 miles or a year, whichever comes first. The only one we've had to change so far was the 1500, and it came out looking like it was hardly used. Granted, I can't perform any oil degredation tests on it, but it seems to me that the 3000 mile point was established many moons ago and was never changed to reflect the abilities of newer engines.

As far as brands of oil go, I've only tried different brands in a pro-stock car that I help work on. These oils have a lot more in them, things that aren't street-legal (exp. zinc, its too polluting), but I've found quite a bit of difference between brands. One brand I used (years ago, not for sure about the name, but it might have been Mobile) was waaaaaay to fast. It ran down through the engine faster than I could pump it back up. Almost cost us the engine. Still, thats racing oil, not street oil.

As far as the reliability of Consumer Reports, I lost faith in them a long time ago. My father used to be a photographer for an architectural firm, and CR did a report on cameras. He said what they reported was....pseudo-accurate. He said that their report, while being truthful, showed that they only did simple tests and didn't take the time to learn about the individual cameras and how to use them. (They werent' point-and-shoot, they were testing semi-pro models) Anyway, that, compiled with things I've read, they've since lost some credibility with me.

 

My company owned 18 wheeler had to go in for warranty work and I was given a rental that had all the perks. Oil temp. gauge was what I kept my eye on. In running at highway speeds, pulling hills with 40,000lbs, dropping 3-4 gears making the engine work. The temp stayed around 125 degrees. Outside temp was from 25- 55 f. Only time temp came up to 185 was at idle, extended idle brought it up to 215. Water temp at idle was from 185 to 210. Not sure where sending unit was located at.

My thinking on oil wear out was changed, I knew idle was no good, thought mainly gas dumping past rings, but also thought hard running would scorch oil. I still do my 2-2500 mile change on own truck, oil is cheaper than sample checking, plus I like that fuzzy feeling.

Just never thought oil would heat up so much during idle.

You know what they say!,,,,,,,,,,,I don't know, I was hoping you would know!

 

I agree with your post and about different types of oil. I have an '88 Cougar that has 300K miles on the engine and the valve covers and oil pan have not been taken off. It's probably had a dozen different brands of oil in it and as long as the oil has the good rating (currently SM) I don't worry about it.
WITH THAT BEING SAID, unless they've recently done another test recently, that taxi test is quite a few years old. Plus, taxi fleets normally run all day, or all night, or maybe sometimes 24 hours a day without the engine or the engine oil ever cooling off. Plus, when they are parked they are usually parked inside away from the extreme weather. Most engines today last way longer than 60K miles anyway. Compared to oil 20 or 25 years ago, I think modern oil has come a long way and I'm not afraid to use about any brand out there.

 

Here's something interesting from Consumer Reports:
Consumer Reports, with one of the most widely respected product testing laboratories in the world"

Cough, cough

 

that CR report is almost 10 years old and no one repects CR's opinion on anything. i don't!