Oil change gauges and accuracy


My car has an oil change gauge that somehow calculates the health of the oil.

I have noticed that when I pass the mileage that the shop recommends that the gauge is estimating my oil health at 83% or so.

I do not enjoy getting my oil changed but is a quick and cheap process so I feel silly wondering if I should wait until the gauge estimates the health as being a bit lower.

I was wondering if I should trust this estimation or if I should just sigh and spend more Saturdays reading the Better Homes and Gardens, March 2001 issue, as I wait for the oil to be changed.

What is the oil gauge actually measuring? The manual just says that it calculates based on temperature and average speeds.

What is the oil gauge actually measuring? The manual just says that it calculates based on temperature and average speeds.
That’s exactly what it does. There’s no sensing of the oil involved. You could put 20K miles used oil in there and reset the minder and it would tell you that you had 100% oil life left.
Personally, I think that most of the minders are pretty good and are safe to go by. How often does your “shop” recommend? 3K is too soon. 5K is okay, but depending on your driving, you may be able to go more.

3,000. I usually go around the 4,500 to 5,000 mark even if the oil gauge is still estimating that it is fine just because I start getting nervous.

Thanks for your help.

If it makes a difference, I do a fair bit of highway driving but I live in the Bay Area so often times highway driving is moving at 20 mph or less. I do a fair bit of just running to the store/mall as well.

I have a 2010 Cobalt. Based on the OLM, the car could go 9k miles between changes. I’m doing 5k oil changes on the Cobalt, personally I’m not comfortable with a larger interval and a 5k interval is easy to keep track of. Previously I changed the oil at a 4k interval.

Very little highway miles or stop and go driving, mostly commuting to work and running errands in a semi-rural part of South Jersey. Average speed 40-50 mph.

Don’t forget to check the oil level between changes regardless of the change interval. The OLM does not monitor the oil level only its life expectancy.

Ed B.

Those GM oil life monitors seem to be pretty good, I’ve seen cases where folks have confirmed the monitors through oil testing. Highway miles are the easiest on the engine, so it’s not surprising you get some long intervals recommended. I’d have no problem going 7500 miles if confirmed by the OLM. Others will recommend 5000. Given the OLM, I see no reason to go less than 5000 if the OLM says you have lots of life left.

I really don’t know if the monitors are good or not. They haven’t been around that long and I don’t know of any car with them that’s reached the 300k mile mark.

The other problem with them is…mechanical/electrical parts DO FAIL. If you change your oil every 5k miles…you won’t have to worry about the monitor system failing. I’ve kept 4 vehicles past the 250k mile mark that way…with 3 of them over 300k…and last I knew one of them had well over 400k miles…So the system of changing the oil every 5k miles WORKS…And it’s pretty simple.

I have a GM vehicle that spent its life on the oil monitor (resulted in oil changes in the 6500-8000 mile range) and judging by what you can see without tearing anything down (e.g. under the valve cover) it is the dirtiest engine I have ever seen. My Ford with many more miles on it and 3-5K oil changes is pristine.

If this car is a lease or you are the kind of person who regularly trades in after several years then just follow what GM says to do (i.e. follow the system).

If you want to keep this car indefinitely - as long as humanly possible - I’d suggest not going past 5K miles.

The oil life systems have been extensively tested. What has been learned through all of that is that they do what they were designed to do. What is still completely unclear is whether this actually maintains an engine just as well as more traditional means (such as using mileage intervals).

This has been discussed ad nauseum before. You can use the search button to find multiple discussions. All you will find here is disagreement, argument, counter-argument, etc. That’s not bad - you just won’t end up knowing what to do - but you’ll probably know a lot more.

My 2000 Ford Explorer has an OLM in it, and I use it. Currently has 206,000 miles on it and no signs of excessive wear or oil burning issues. BUT, I use a fully-synthetic oil instead of the Motorcraft semi-synthetic the dealer uses. Since I change the oil 3 times a year, based on the OLM, I don’t mind the extra cost.

I had my oil tested last year. My Mobil-1 EP at 8800 miles would have been good to 10,000 miles ON MY DRIVING PATTERN and on my 2002 Sienna with 173,000 miles. I change now at roughly 8,000 miles. I think 83% is close enough. It can be false economy to run to the limit. Though I am one who believes oil for many people gets changed too often, in the end if you change it twice as often as needed, it is not a big deal financially compared to the large number of morons out there who destroy their engines by not changing it often enough.

Most people who have never had their oil tested are just plain guessing when to change it. That is not a problem at all, unless they try to push their guesses as gospel.

Don’t wait for the indicator, it might work and it might not. Some engines fall apart before the oil change indicator reaches zero. Whatever the monitor monitors, I don’t believe that it is the actual condition of the oil. That would be a $20,000 option if it could be done. Then we could afford to not choose it as an option and just replace the engine three times in 150,000 miles. The car companies are trying to sell us on the worst possible device.

I would guess the car companies are trying to do two things.

First the advertising department loves it as it will give them something to help them sell the product. The manufacturer also can rightly suggest that it is the driver's fault if there is an oil related failure and the owner had not changed the oil when the car asked for it.

I would change oil when the OLM reads 50%.

I think the OLM can work well, but it cannot account for an engine that is running low on oil.
The reduced volume of remaining oil has to work harder.
So check that dipstick every other tank of gas.

Quote: “The car companies are trying to sell us on the worst possible device.” Unquote

This and the oil companies robbed us of the 200 mpg carburetor in the 1930s.

Mr. PDV2, you should understand that in the light of present day competition, car makers have customer satisfaction as their most important goal as it is vital to continue earning a profit for their stockholders. After the oil life simulator program has been proven for a long enough time, second guess armchair engineering judgment will fade away.

These monitors have been in customer usage long enough for fine tuning if required but I have not heard that was needed.

“car makers have customer satisfaction as their most important goal”

I’m astounded. This would explain all of that GM piston slap? And all of those LIM gasket problems? And incredibly weak and wimpy transmissions in minivans? And absolutely ridiculous recommendations regarding things like transmission service (that every rebuilder knows are bad)…

Anyone who believes this kind of nonsense gives consumers way too much credit for how much they know and take into account when they make decisions. A philosophy of “You can naturally trust auto company recommendations and devices because of market competition” is laughable on its face…and, I might add, dangerous.