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Posted: Wed Apr 09, 2008 3:13 am Post subject: My car's "change oil" light

Hey guys, after a discussion with my mechanic, he said something that sounded odd to me, and I wanted to get you guys' opinion on it.

I mean, the more I think about it, he really should know what he's talking about. But what he suggested to me sounded so conspiratorial it made me wonder.

What was it, you ask?

Well, he and I were discussing the "change oil" light on my car ('99 Olds Alero). In a nutshell, my light came on prematurely (it usually comes on between 4500 and 5500 miles which is about 5 - 6 months of driving for me - this time it came on after 2500 miles and 2 1/2 months).

I was under the impression that the light was connected to a sensor that somehow can tell (based on the quality or dirtyness of the oil or something) when I'm truly due for an oil change. Rather than going the standard 3000 miles/3 months that we've all heard for years (which I understand is based on the lowest-common-denominator, since some driving styles require oil changes sooner than others).

What he said is that the light is nothing more than essentially a mileage "timer"... That when my oil is changed, the timer is reset, and it turns back on when a set amount of miles has passed on the vehicle (probably around 5000 based on my experience with my car).

When I asked him why it'd be a timer instead of a sensor, he told me that it's because the auto manufacturers really like the "new every two" idea, and by telling people they really DON'T need an oil change at 3000 miles, but rather at 5000 - 7500 miles, it reduces the life of the car, forcing them to buy a new one sooner.

Now, that sounds suspicious to me.

Anyone here know if there's truth to it?

Oh, and with regards to the original problem, my mechanic suggested that probably last time I had them do an oil change for me (2 1/2 months and 2500 miles ago), they must have forgotten to reset that "timer", which is why it's turning the light on now. Now while this does support the idea that it's on a "timer" (if it were a sensor, they shouldn't be able to turn it off without doing an oil change, I would think), it does pose another question: if I was around the 5000 mark last oil change (which is probably about right), even if they forgot to reset the timer, it shouldn't have gone 2500 more miles - maybe 500 at most. So in other words, something just doesn't add up.

Posted: Wed Apr 09, 2008 4:02 am Post subject:

The lights are based on mileage. I don't know how you reset it on your Oldsmobile. For a Honda, you hold down the trip odometer reset button while starting the car and keep holding it down for 10 seconds afterward (until the indicator lights stop blinking).

Posted: Wed Apr 09, 2008 4:17 am Post subject:

JustAnEngineer wrote:
The lights are based on mileage. I don't know how you reset it on your Oldsmobile. For a Honda, you hold down the trip odometer reset button while starting the car and keep holding it down for 10 seconds afterward (until the indicator lights stop blinking).

It's funny, he told me the way to turn it off was to turn the ignition to AUX, and push the gas pedal three times - he said it would make the oil light blink and then turn off.

Oddly enough, that didn't work (I assumed I missed a step, since I was doing it from memory after talking to him earlier in the day and wasn't smart enough to write it down). So now that I look on the internet, I see that I should use the "reset" button in the fuse box by the driver's door (which I'm familiar with, as I used that periodically to reset the "low tire pressure" light back when I had a slow air leak in one tire).

Still, it's disappointing that it's not a sensor, telling me when the car TRULY needs new oil. I'm a little bummed.

Posted: Wed Apr 09, 2008 4:34 am Post subject:

Actually for the auto manufactures would tell you that you don't need an oil change untill you've gone between 5000 and 7500 miles....... a replacement car means more money in there pocket and more out of your pocket.

Posted: Wed Apr 09, 2008 5:04 am Post subject:

the taz man wrote:
Actually for the auto manufactures would tell you that you don't need an oil change untill you've gone between 5000 and 7500 miles....... a replacement car means more money in there pocket and more out of your pocket.

Right, that's what I meant by how they want us to be driving "new every two"...

Posted: Wed Apr 09, 2008 6:43 am Post subject:

Alphi wrote:
JustAnEngineer wrote:
The lights are based on mileage. I don't know how you reset it on your Oldsmobile. For a Honda, you hold down the trip odometer reset button while starting the car and keep holding it down for 10 seconds afterward (until the indicator lights stop blinking).

It's funny, he told me the way to turn it off was to turn the ignition to AUX, and push the gas pedal three times - he said it would make the oil light blink and then turn off.

Oddly enough, that didn't work (I assumed I missed a step, since I was doing it from memory after talking to him earlier in the day and wasn't smart enough to write it down). So now that I look on the internet, I see that I should use the "reset" button in the fuse box by the driver's door (which I'm familiar with, as I used that periodically to reset the "low tire pressure" light back when I had a slow air leak in one tire).

Still, it's disappointing that it's not a sensor, telling me when the car TRULY needs new oil. I'm a little bummed.

In my experience with my GM truck, it isn't really just a timer, but an actual calculation based on the driving style. This is what the manual claims, but I didn't believe it, so I have carefully tracked when the oil change light came on. I've actually completely ignored the light and just changed the oil every 5000km, but I've tracked the light. For me, the minimum distance for the light to come on was just over 5000km. There was a bunch of towing done that time, including towing a 5,000lbs truck on a flatdeck for 700 km. It usually comes on after around 10,000kms for me, but then, if I'm not towing something, it is strictly highway miles. If there is more city driving done than usual, the distance is less.

And for my truck, you reset it by putting the key to the "On" position without the enginge running, and press the gas pedal to the floor three times. That will make the light blink, and then press the gas pedal to the floor three more times to reset it.

Guide Dog Joined: 08 Nov 2003 Posts: 8371 Location: MN

my oil light came on when the quick oill place fucked up and didn't put in the right amount of oil... (low oil was the problem) on my parents saturn it is just a milage timer. I've never had mine come on with out being low on oil though. (reset from the fuse box on my parents saturn)

as for 3k vs. 5k ... I have a hard time believing that it makes the slightest bit of differance any more. the drive train isn't going to be the place where your car fails to the point of replacement more then likely. Having see so many people just add a quart when the quart low light comes on for well over 120k on the car, before selling it (not because of the power train but because of the rust) i doubt that changing your oil is near as important as what people would have you beleive (that being said, it used to be a much larger deal, but with new oil and new motors, That is what i'm talking about.)

that all being said I change my oil ever 5k like the manual suggests.

Posted: Wed Apr 09, 2008 3:14 pm Post subject:

I put allot of highway miles on my car and normally don't end up changing the oil for 4000-5000 miles, and I haven't had an engine problem yet.

I bought my car about 3 years ago with 70K and now my car is pushing 150K, so about 27,000 miles a year...more than 2x the average Shocked

Posted: Thu Apr 10, 2008 7:44 am Post subject:

Theres a button on the drivers side dash in the fuse box panel to reset the change oil light. Like Hummer said, it's really based on driving style, theres no timer, theres no sensor really, the ecu just does a calculation based upon throttle load. If your foot is in the skinny pedal more, the light comes on sooner.

Posted: Thu Apr 10, 2008 8:03 am Post subject:

Well then let me ask you guys this:

How often *SHOULD* someone change the oil in their car?

Is it around 3k miles/3 months, as we've been told for years?

Or is it more towards 5k miles, as the auto manufacturers have started saying in the last several years?

I guess the real question is this: are the auto manufacturers changing from 3k/oil change to 5k/oil change because of improvements in the vehicles and oil over the years allowing the additional mileage?

Or are they just trying to "wear out" cars sooner so we have to buy more often?

Posted: Thu Apr 10, 2008 8:45 am Post subject:

I would think that changing the oil every 3k to 5k miles is fine. It really depends on what you are doing with the vehicle. The harder you work it, the more frequently you should change the oil. All city driving? Probably closer to 3K. Only highway? 5K or more.

Posted: Thu Apr 10, 2008 9:21 am Post subject:

check the oil ever so often... when it gets dirty... change it.

should take about 3-5K to get black, but like has been said... depends on the driving. If you're doing lots of heavy towing... you may even need to change the oil after only 2K

Posted: Thu Apr 10, 2008 10:39 am Post subject:

I run full synthetic (Mobil 1) and still change every 3k miles. Funny thing is, I remember when 6 quarts of Mobil 1 and a filter cost more than a tank of gas, not so much anymore. Crying or Very sad

And yes, my little 4 banger takes 6 quarts of oil.

Posted: Thu Apr 10, 2008 12:48 pm Post subject:

smokinAMD wrote:
And yes, my little 4 banger takes 6 quarts of oil.

Wow. My 6.0L V8 takes six quarts of oil. Both of my 4-bangers are a bit less than 4 quarts.

Posted: Thu Apr 10, 2008 2:28 pm Post subject:

What's with the whole "3 months" thing anyway? Does oil really break down that much in 3 months that you would need to change it regardless of your mileage?