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Percent Oil Life

How reliable is the oil life percent indicator in my Chevy HHR? When I use this as a guide for changing my oil it is a lot more time and miles between oil changes than when I rely on the sticker the oil change folks put on my windshield…

Never let a computer tell you what to do…Oil is cheap. Replacement engines are not. Stay out of 'Quick-Lube places…

If in doubt, go by your owners manual. The oil change place wants you to come early and often. They probably say 3 months or 3000 miles, which is obsolete.

Personally, I go with 6 months or 5000 miles even if the manual calls for longer intervals.

I agree with both Caddyman and Circuitsmith on this. Forget the computer, follow the manual…but max out at 5,000 miles or six months. And avoid quickie lubes.

Note that we’ve had long threads on this subject and we don’t all agree, but I personally don’t like to try to extend oil life. I’d rather extend engine life.

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Do a compare and see how it does. Accounts from Chev owners say it seems to work OK. Also keep in mind what folks put on stickers (ranging from 3K to 5K miles) can be self-serving. I personally like 5K oil changes on conventional. My engines do fine, and if the OLM comes close to that, then it is one more memory device I can use as a reminder.

The problem with following the manual is that it will probably tell you to follow the “oil life” system - or whatever it is.

As others have said, I would ignore the computer and go with 3-5K miles or no more than 6 months. I have a GM vehicle right now. I bought it with 100K on it and the prior owners followed the “oil life” computer religiously. Judging by what you can see through the oil cap - that engine is the dirtiest and gunkiest one I’ve ever owned. I have a Caravan with about 217K on it and it is much cleaner. I am not a believer in GM’s “oil life” baloney.

I have a 2006 Chevrolet Uplander and it has the oil life percent indicator. I don’t know how it’s programmed, but in the winter when I do a lot of stop and start driving, it tells me that the oil is ready to be changed after about 3000 miles. In the summer when I am driving longer distances, it doesn’t show that the oil needs changed until about 6500-7000 miles. This makes sense to me. Stop and start driving when the engine takes longer to warm up is much harder on the oil than warm weather open road trips.

When the oil life is down to about 4%, it displays the message “Change Oil Soon”. When it gets to 1% left, it gives a stronger message and the chime dings to call my attention to it. I’m certain that the percent indicator doesn’t know what kind of oil is in the crankcase. One garage put synthetic oil in last November. The minder said I needed a change around 3000 miles, just as it did with regular oil in the winter months. The oil minder just confirms what I have always done with my cars–change more frequently in the winter under stop andgo driving and less frequently in the summer with longer runs.

The GM oil life computer is actually a pretty nifty thing. It actually records how much highway vs. stop-and-go driving you do and how many cold starts, etc. and actually gives you an indication of when you really need to change your oil, as opposed to the arbitrary mileage between changes, which assumes more severe driving than most drivers do. There’s no reason not to go with the computer figure-- it still has a certain buffer built in so even if you go past 0% your engine’s not going to blow up or anything.

I think GM should play this feature up more-- most of the other brands’ oil change lights just come on at set mileages and the GM system can reduce maintenance costs substantially if you do a lot of highway driving.

The oil life indicator is the best way to go . Unless you like wasting money and oil . What it looks at is cold starts and that’s where the severe service comes in .
Mechanics are very conservative ( and profit oriented ) .

the sticker the oil change folks put on my windshield…

And you are surprised they would recommend oil changes sooner than needed?

The real authority here is found in your car’s owner’s manual. It contains all kinds of great information. Give it a read some day.

Many people today, especially older guys like me, will tend to suggest doing more oil changes than are really needed.  Modern cars and modern oils are far different than they were back in 1965 when I bought my first car.  

Today car manufacturers are recommending longer oil changes and cars are lasting longer than the manufacturers.  Very very few cars end their life due to any kind of oil failure other than having the drain plug fall out etc.  

If that indicator is OEM then I would tend to accept it.  I would not trust an after market meter.  

In any case follow the instructions in the owner's manual and be happy. 

Don't ever take your car to a quick oil change place, even if you are only looking for directions.

On the same topic, I have always changed oil every 3K mile. Recently I myself changed my '05 Camry for the 1st time. Noting that the oil filter was vertical, I decided to fill it with oil before installing to reduce the lack of oil on the 1st start after the oil change. Low and behold the 1st start still had the annoying sound of oil deprivation. If I am changing the oil every 3 K mile vs every 6 K mile, I am doubling the harmful effect of these starts. SO are we really extending engine life or reducing it by changing oil more frequently?

I never follow the sticker, it’s a self serving advertisement of the oil change place. The computer is able to monitor the number of starts, lengths of trips, and temperatures to come up with a very good estimate of oil life. I am aware of no study supporting 3000 mile changes. Do extra oil changes hurt the car? Of course not, but they waste oil and money. I’d follow the monitor.

Pay to have the oil analyzed after you change it. First, change it according to the sticker, 2nd time, change it according to the computer. This will give you a more accurate measurement to change your oil by

That is an interesting idea. I have never subscribed to the concept of regularly paying the price of an oil change to have the oil analyzed instead of just replacing it. But, to pay for analysis once or twice to develop confidence in the automatic system, that makes sense. Maybe once in the summer and once in the winter.

I believe you have made this statement before, and yes, for a car it does not pay to do this frequently.

However, it is useful to do it once or twice to see how your car behaves when oil is changed as per the manual. I had a small block V8 Chevy and using regular brand oils , I changed the oil every 2500 miles during the winter. The analysis ($15) showed 46 parts/millon metal contaminants, oil viscosity within range, total acid/base number OK, no water or glycol in the oil (indicating no leaks), and no excessive carbon, indicating good combustion.

EXXON condemns oil at 200 parts/ million!!! So I had lots of spare oil life left. The EXXON rep told me to go to 4000 miles at least, since I was parking inside, using a block heater when parking outside, and my driving included lots of longer trips to blow off condensation.

Some engines sludge more than others, and I recommend anyone to have their used oil tested to ensure you are changing it at the right interval. This is very much a function of your driving pattern.

Gabriel does not fly down with a paper and give it to the manufacturer telling how often to change the oil on a given car. You can be sure that engineers, or perhaps actuaries, figure it out, and you can be sure there are all sorts of complicated math and statistics/probabilities involved.

In the 50’s or 60’s Tom McCahill, automotive writer of that period, told of an experiment done by a NYC taxi company, assigning different taxis different oil change cycles. Of course, engines are better today, and so are oils. So, the numbers they got are not good any more. The concept they learned is the same today. Note I am going by memory, so it is possible I have an error in the numbers; as I said, the concept is the important thing.

Some taxis got oil changes every 1,000 miles, which was recommended in those days. Others got assigned up the ladder, each step more miles before changing. Finally, a group never got the oil changed at all, just checked and topped off when it was needed.

The 1,000 mile oil change group got 100,000 miles before an overhaul, which in those days was still considered good.

The greater distance between changes, the shorter the miles before overhaul.

The cars that got no changes at all, lasted, as I remember it, at around 40,000 miles the engine was toast. Any old timers know for sure? I have a couple of his old magazines to this day, I ought to dig around and look it up if it is in those magazines.

I know engineering, having worked with a number of brilliant engineers over the years. You can be sure they did some testing, like described above, and management made a business decision based on a number of factors. I am sure buried somewhere in those car companies’ vaults are charts and tables, telling just how long different mileage changes keep the average motor running without repairs.

Including how long the average new car owner will keep the car. Including what they estimate – or know from marketing studies – the driving patterns of the average owner will be. Including how much attraction to new car buyers a given long change cycle will induce.

Then, they pick what they perceive as optimum, with emphasis on “longer is better for sales” while looking at the company’s reliability goals.

If you are within their predicted marketing ranges, as far as your driving patterns, and just how long you plan to keep the car, then you should accept manufacturer’s recommendations. I suspect most new cars get traded long before 150,000 miles. For American cars, that has been the expected life of the motor, though if it has changed in recent years, I have been mostly out of the country.

If you are like me, and expect to keep that car 250,000 miles or more, changing the oil more often for your driving conditions is probably NOT a waste of money.

If you understand the principles, you can change your mileage for changes to suit yourself. For example, I drive mostly on the highway. A majority of my miles is put on in about three weeks of days spread over the year, and virtually none of that in cold weather. I use Extended Performance Mobil-1, and changes vary from 5,000 miles to 8,000 miles, though once I forgot and went 10,000 miles. It still looked good, though that was an accident caused by a clerical error.

If you drive 5 miles a day, year round, in the winter if you want to keep that car a very long time, like Jack Benny’s Maxwell, you had better forget mileage, and change it every month or two, even if it has only a couple hundred miles. Those cold starts and never a warm-up are murder, even on new metals.

As someone said, the cost of those changes really isn’t that much. My dad used to say, “Penny wise and pound foolish.” This was amazing, because he was the world’s best example of that old saying.

I do agree, don’t hit the chain places nor China Outlet stores. Speaking of statistics and probabilities, the odds of your motor making 250,000 miles with some high school kid changing the oil for you are very low. Better to drive it without changing, heh, heh.

That’s interesting detail, Docnick. I have had a really good impression of you, since you were one of the few on the board who actually understood my high-rel maintenance program for my 2002 Sienna, based on my distance from Toyota parts and competent mechanics here in rural Mexico.

Maybe I will try mine at one time, just to see how I am doing, if I can find a convenient place to do it. 152,000 miles now. It should be broken in now.

I am doubling the harmful effect of these starts. SO are we really extending engine life or reducing it by changing oil more frequently?

According to my calculations the dry start up is costing you 3 minutes of engine time for each oil change. The more frequent oil changes are adding 180 seconds of engine life. :slight_smile:

Muchas Gracias, irlandes; you can begin by taking the oil cap off your car tomorrow morning (engine cold) and sticking your middle finger in the opening, running your finger over the inside of the valve cover. If the oil has been changed religiously and at thre right interval, your finger should only have clean oil without any sludge or grit on it! The oil can be amber or dark depending on the miles on the oil.

When shopping for a used car this is a quick test; the guy selling it probably just changed the oil, so you can’t tell from the dipstick.

The way you maintain your vehicle is very similar to the way oil companies do it in the Middle East (very hot and dry) and the Arctic (very cold, lonely and dangerous), as well as the military. I was trained in the army in preventive maintenance under combat conditions. We did not take chances!

Your engine should be good for at least 250,000 miles without internal work, but expect several timing belt and water pump replacement. We maintained a 1984 Chevy Impala V8 that way, and when we finally sold it after 20 years, the family had put over 300,000 miles on it and the valves and rings were still fine, but the valve guide seals were leaking some oil. The car still had 95 % of its original compression. Only the timing gears/chain and the water pump had been replaced. The transmission was still as good as new. The car was still reliable from day to day.

Actually craig58, who we have not heard from lately, maintained his 2 Mercedes cars that way as well, since they were 20 years old and parts were not instantly available.

In the maintenace professsion there are several types of maintenance:

  1. Run-to-failure (don’t maintain, replace); very expensive

  2. Regular preventive maintenance; much bettter, lower failure rate

  3. Predictive monitoring (checking things, oil analysis) with preventive maintenance routines; identifies impending failure and tries to prevent it from happening. Heavy industry practices this with expensive and critical equipment.

  4. Pro-active failure prevention; implement items in #3 and go after the remaining weak areas and beef them up to prevent failures from happening. This is the modern failure prevention type of maintenance and was origiated by the Japanese as well as the US aerospace industry. I implemented this in the Arctic to keep from freezing to death!

When consumer reports did their taxicab test, they concluded:
"Even in the severe driving conditions that a New York City taxi endures, we noted no benefit from changing the oil every 3,000 miles rather than every 6,000. If your driving falls into the “normal” service category, changing the oil every 7,500 miles (or at the automaker’s suggested intervals) should certainly provide adequate protection. (We recommend changing the oil filter with each oil change.) "

You can read the entire article here: