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2005 CTS
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Discussion Starter #1
Good Lord, I just checked my oil at 5k past the last oil change and had to add three quarts and could have used one more! :wtf:

Is this normal? I just bought a case of Mobil 1 to keep in reserve between oil changes.

The engine only has 43k miles on it.

What are your experiences with this?
 

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cts
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same thing happened to me two weeks ago - checked the oil and was down 3.5 quarts, and the computer said i was at 28 percent oil life. My understanding is that this engine uses oil to the tune of 1 quart every 2000 miles. check early and check often. i will be selling the car soon and am worried that when I disclose this fact it will scare away any potential buyer, yet my conscience wont allow me to not disclose it lest a buyer drives unaware and seizes the engine.
 

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2006 STS V8 1SF RWD
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GM says that 1 qt/2000 miles is "normal" for an engine to burn, I do not agree but that is what they say. I recommend checking your oil at every fuel fill just to be safe, I learned to do that routinely after owning 2 Northstar powered Cadillac's previously. Those ladies were thirsty SOB's :)

Also, DO NOT follow your OLM, it will KILL your timing chain. I had my CTS in for a routine rotatation/roadforce balance this last weekend and was talking to the head tech about common issues. He said that most, if not all, of the timing chains they have seen in there have been from owners who followed their OLM to the T. I will never go more than 6k in between oil changes, synthetic or not.
 

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2006 CTS-V
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Sounds like they need a reflash. With the 3.6 / 2.8, I'd be especially careful and change my oil every 3k... Considering the timing chain issues.
 

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Also, DO NOT follow your OLM, it will KILL your timing chain. I will never go more than 6k in between oil changes, synthetic or not.
Your suggestion is just as dangerous. The GM OLM is the best in the business. If you dont follow it, you are ignoring a very valuable source of info. The OLM is highly accurate with regards to the life of the oil and is more accurate then what Audi BMW and Mercedes have to offer.

If you choose to change the oil every 6k miles, you are not taking into account the variances in driving from week to week, month to month. Oil that goes through 6k miles of hard stop'n'go traffic and the odd track day, will be in much worse shape then 6k miles on oil that only sees steady state highway miles.

GM's tolerances are the problem here. Instead of ignoring something so brutally accurate as the OLM (you can get a UOA to prove that GM's OLM is fantastic) use it to your advantage. Instead of changing the oil every 6k miles, change the oil when the OLM reachs 10%...20% if you want to be safe. 50% if you want to be really safe. At least this way, you are changing at a more consistent interval. The OLM takes more factors into account then just distance, RPM's being one of those factors. Miles are irrelevant compared to how the oil was actually used.


Just to Nit Pick. 1qt/2000 miles is normal for this engine. Its just not ok. ;)
 

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08 White Diamond CTS DI RWD FE2 all options
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concorso,

I am not sure about OLM accuracy. The second generation of CTS just had a recall that reprogrammed the ECU resulting in OLM counting down twice as quick! And yes, it was due to timing chain issues. So I do not trust OLM anymore and will change oil at 5k - 6k intervals.
 

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2006 STS V8 1SF RWD
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Your suggestion is just as dangerous. The GM OLM is the best in the business. If you dont follow it, you are ignoring a very valuable source of info. The OLM is highly accurate with regards to the life of the oil and is more accurate then what Audi BMW and Mercedes have to offer.

If you choose to change the oil every 6k miles, you are not taking into account the variances in driving from week to week, month to month. Oil that goes through 6k miles of hard stop'n'go traffic and the odd track day, will be in much worse shape then 6k miles on oil that only sees steady state highway miles.

GM's tolerances are the problem here. Instead of ignoring something so brutally accurate as the OLM (you can get a UOA to prove that GM's OLM is fantastic) use it to your advantage. Instead of changing the oil every 6k miles, change the oil when the OLM reachs 10%...20% if you want to be safe. 50% if you want to be really safe. At least this way, you are changing at a more consistent interval. The OLM takes more factors into account then just distance, RPM's being one of those factors. Miles are irrelevant compared to how the oil was actually used.


Just to Nit Pick. 1qt/2000 miles is normal for this engine. Its just not ok. ;)
I've never let that thing get lower than about 30-35%, just can't do it.
 

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Considering the timing chain issues that may have to do with this, and also considering how it burns thru oil in those engines, yeah, I'd be doing it much sooner.
 

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cts
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Debating when to change the oil is well and good, but my concern is how you can literally run out of oil and not know it till it is too late? If the computer is so smart as to monitoring the condition of the oil, why cant it warn you when the oil level is below a certain point?
 

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concorso,

I am not sure about OLM accuracy. The second generation of CTS just had a recall that reprogrammed the ECU resulting in OLM counting down twice as quick! And yes, it was due to timing chain issues. So I do not trust OLM anymore and will change oil at 5k - 6k intervals.
It wasnt just the 2nd gen. CTS that had the recall. It was also the 07 CTS, SRX, Enclave, Outlook, etc... Per GM's descriptions of the recall, they simply lowered the interval... You will travel about 2k miles less to reach 0%, now. Changing at 5-6k intervals is not safe enough. 2 summers ago, my OLM read 17% after 4.5k (thats kilometers...about 3k miles) after 3 full months of really hard driving. If I had followed your OCI, my oil would have been well past its safe limits. Presently, Ive travelled 9.5k kms, and the OLM reads 14%.
The OLM is accurate in the sense that it is consistent. Ive been changing at the same % every time (since my 2nd oil change at 2000 miles) and Ive gotten a UOA each and every time. The results have always been practically identical. The problem with the OLM is that 100% - 0% is equal to about 9k miles travelled, for ex, when it should equal 7k miles, the scale is too large. That is exactly what GM is changing with the recall.

The OLM measures crankcase temperature, RPMS, moisture, throttle position, etc. It will give you a consistent reading every time, even if the intervals are too great.

FWIW. My CTS has 115k km's on the odom, and I dont burn a drop of oil. Ill trust a UOA and a modified interpretation of the OLM long before Id trust a distance as the only factor...
 

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Debating when to change the oil is well and good, but my concern is how you can literally run out of oil and not know it till it is too late? If the computer is so smart as to monitoring the condition of the oil, why cant it warn you when the oil level is below a certain point?
The computer doesnt monitor the condition of the oil. It monitors how the engine operates and some of the conditions inside the engine. You should check the oil level frequently.
 

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I've never let that thing get lower than about 30-35%, just can't do it.
Thats reasonable enough. Its just much safer, imo, to trust 30% then it is to trust a distance, like 5k. Trusting a distance doesnt take into account the variances in how an engine is used.
 

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Oil Life Monitor --
How Does It Know?


How long will oil last in an engine? What reduces the oil’s effectiveness? When should it be changed?
Lubrication engineers perform a number of tests to answer these kinds of questions. Vehicles are operated under prescribed conditions, and periodically a sample of the oil is taken into the laboratory for analysis. When the condition of the oil is no longer satisfactory, the mileage is noted. From controlled testing like this, engineers in the past have determined two sets of mileage numbers, one number for normal driving and the other for severe conditions. Severe conditions can mean that the vehicle is driven hot (for example, pulling a trailer up a mountain) or is driven such that the oil never warms completely (for example, trips
less than 5 or 10 miles in a winter climate). It is then up to the owner to decide whether their own driving is normal or severe and to change the oil accordingly. Now, science and technology have found a way of taking the guesswork out of the picture.
GM is installing an oil life monitor in an increasing number of new vehicles. Using a simple indicator lamp or readout on the
instrument panel, this system notifies the driver when to change the oil.

Additives
Straight oil is not an ideal lubricant in an engine. A package of additives is needed to give the oil properties it does not naturally
have or to enhance its natural properties. Some of the tasks accomplished by additives: - viscosity modifiers, to keep the oil the
proper thickness over a wide range of operating temperatures - anti-oxidant, to keep the oil from thickening - corrosion inhibitors, to protect engine components - anti-wear - anti-foam - detergents, to suspend solid particles.

What Makes Oil "Wear Out?"
If you were to start out with a crankcase full of fresh, clean oil, and drove the vehicle for a period of time, eventually the oil would
have to be changed. During this time, what can change fresh oil into "worn out" oil? First, dilution. When gasoline is burned in
the combustion chamber, the by-products include a lot of water. Some of this water can find its way into the crankcase through piston ring blow-by. If the engine is cold, and if combustion is not perfectly complete, a small amount of acid is formed. It, too, can blow-by into the oil. You don’t need to be a top-notch scientist to realize that water and acid aren’t good things to pump through the lubrication system of the engine. If an engine is run long enough for the engine oil to warm, the water and acids will evaporate and not accumulate. But, during very short trips in cold weather, water and acids can enter the engine oil and
cause the oil to "wear out." Second, the degradation of the oil and its additives. We mentioned earlier that a number
of additives are put into oil to improve its performance. If these additives are degraded or decomposed, the oil is no longer capable of doing all of its jobs properly. Oil with degraded additives can become thick and dark. Additives become degraded by exposure to extreme heat. There are two places a lot of heat can reach the oil. One is near the combustion chamber. Oil at the top piston ring is exposed to very high temperature. And some bearing surfaces can also put a lot of heat into the oil at high operating temperatures. So, degradation of additives from high temperature operation is the second factor that can cause oil to "wear out."


How Can Operating
Conditions be Used to Predict
Oil Life?

Using carefully controlled laboratory tests, it’s possible for lubrication engineers to measure how long it takes to dilute engine oil
during cold operation. And it’s possible to measure how long it takes for high temperature to degrade the additives. We usually think of measuring time in hours and minutes, but for an engine, the amount of revolutions it has run is also a good measure. So for the purposes of oil life, time is measured in engine revolutions. Engineers like to talk in terms of models. A model is a way to describe something mathematically. It’s possible to create an oil life model that very carefully matches the results of analyzing the oil in a laboratory. The oil life monitor, then, is based on a model. A computer chip in the Powertrain Control Module is loaded with a certain number of engine revolution counts. The count for each engine/vehicle combination is determined by testing. As the engine runs, each revolution is subtracted from the remaining count in the oil life monitor. When the count reaches zero, the instrument panel light comes on. But, here’s the clever part. When the various input sensors detect that the engine is running under either cold or hot conditions, it subtracts extra counts (penalties) for each engine revolution. So, the conditions that cause the oil to "wear out" make the counter run down faster. When the oil is changed, it’s necessary to reset the oil life monitor and the
countdown begins again.

GM Oil Life System Revisited
Briefly, engine oil degrades in a predictable fashion, according to several measurable engine operating conditions. The engine control module counts combustion events (measured in rpm) and reads coolant temperature. From these numbers, the computer is able to track oil deterioration and notifies the driver when a change is needed. The best value from the cost of an oil change is obtained by maximizing the mileage between changes, so long as there is no adverse effect to the engine. With the GM oil life system, the average person can expect oil change intervals of 4000-7000 miles for mixed driving, and 7000 to 10000 miles for highway driving, while the Chevrolet Corvette and the 2002 Envoy, Bravada and TrailBlazer can achieve 15000 miles under ideal
conditions.
Since the GM oil life system first appeared on some 1988 Oldsmobiles, over 10 million have been built, presently at the rate of over 3 million a year. By model year 2003, GM expects to install oil life systems on essentially all cars and light duty trucks.
This past May, the GM oil life system development team was honored by receiving the first ever Environmental Excellence
in Transportation award from the Society of Automotive Engineers. This award recognizes that the extended range offered by
the oil life system can save huge amounts of new oil, and can keep thousands of gallons of used oil out of the environment.
There’s a lot of information on vehicle maintenance shared on consumeroriented websites – some correct, come erroneous, and some simply outdated. For instance, conventional wisdom calls for oil changes every 3000 miles. Not surprisingily, this conservative figure is also supported by those who derive income from selling oil changes. Many of your customers have become
convinced that any longer oil change interval is somehow harmful to their engine. At the retail level, you can do your part by promoting proper use of the GM oil life system. Become familiar with its function, and be prepared to help customers understand that observing the montor’s recommendation is the easiest way to take the guesswork out of oil change intervals. It also ensures
that they are giving their vehicle the proper care it deserves, at the minimum expense.

GM Oil Life System Revisited #2
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. We first told you about the GM Oil Life System in the March 2000 TechLink. Since then, the system has become standard equipment on nearly all GM products.
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 simpified determination about when to change oil. No more decisions about “normal” conditions vs. “severe” conditions. Second is 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.
These benefits will be realized only if engine oil is actually changed as indicated by the GM Oil Life System.
Some customers “get it” when it’s explained to them. Others may be reluctant to deviate from traditional oil change interval charts. So, part of the responsibility falls on retail service people to help get the message out.

There’s More
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. This could result in customers having to bring their vehicles in for an oil change when the light comes on, only to find that the vehicle is due in a month for scheduled maintenance.
That’s all changing. In the accompanying article “Simplified Maintenance Schedules”, you’ll learn how maintenance intervals are now being tied into the oil change intervals indicated by the Oil Life System.
 

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Theres no need to throw the baby out with the bathwater... My OLM's accuracy has been spot on, as proven by numerous UOA's Ive had that say the ZDP levels are safe.
 

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Debating when to change the oil is well and good, but my concern is how you can literally run out of oil and not know it till it is too late? If the computer is so smart as to monitoring the condition of the oil, why cant it warn you when the oil level is below a certain point?
Are you saying that the CTS does NOT have an oil level sensor like my Seville does?
 

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Spyke said:
]

Lightbulb Oil level sensor

I just want to give you the information about a test I did today.

It was time for an oil change when the oil change soon light came on yesterday. I drained the old oil out of the car and put back the drain plug...

I said to myself.. hmmm let see if the oil level sensor still work. Without oil in the crankcase, I turn the key at "on" position. 5 to 10 secs later, "check oil level" came on. Okay its working... My question was this:

WHEN does it warn you?

So I decided to fill the engine with oil, 500 ml per 500 ml. I added 500ml of fresh oil and then, put the key at "on" and check for the "check oil level" message to come on.

2 liters laster, its still working. I added another 500ml: still get the message. I added another 500 ml and the message didnt showed up.

So when does it came "on"? When there's in the crankcase somewhere between 2.5l to 3l of oil. The car is supposed to be between 4.7l (when at the "add" mark on the oil dipstick) and 5.7l (when at the "full" mark). So when its missing about 3 liters of oil, its supposed to show up. Kinda late since its missing 50%.

Just to let you know guys my little experience.

Have a nice day!

Mark.
This should answer your question. He has an 04 CTS IIRC. It has one, but it informs you too late.
 

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Discussion Starter #18
I started out with a question/comment about oil consumption and somehow it changed into oil changes...

This is all very good info for all, but is everyone suffering from the same malady as I am with so much oil being used? I feel like I'm babysitting an R1820 radial engine!
 

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2000 miles to a quart? I'd be happy as a clam with that. I (and a few others on this site) only get 1000-1100 miles to a quart. As soon as the 2yr/24000 mile warranty expires on the transmission I had to put into this heap, I'll be selling it. Yes, the tranny that others on this site call "bulletproof", went south at 75,000 miles. This car is not abused and has never towed anything. Oh and did I mention the rear diff whines like a banshee between 45-65 mph - yes the fluid has been changed. Oh and did I mention the EBCM module failed at 65,000 miles. There's more but I'll stop. Best of luck with your car. I'll be buying Ford or Korean next.
 

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2000 miles to a quart? I'd be happy as a clam with that. I (and a few others on this site) only get 1000-1100 miles to a quart. As soon as the 2yr/24000 mile warranty expires on the transmission I had to put into this heap, I'll be selling it. Yes, the tranny that others on this site call "bulletproof", went south at 75,000 miles. This car is not abused and has never towed anything. Oh and did I mention the rear diff whines like a banshee between 45-65 mph - yes the fluid has been changed. Oh and did I mention the EBCM module failed at 65,000 miles. There's more but I'll stop. Best of luck with your car. I'll be buying Ford or Korean next.
Someone doesn't like their Cadillac.....All cars breakdown, parts don't last forever. If you can find me a car with 100,000+ miles on it that has never had any issues whatsover I'd be shocked.

Enjoy your Ford or Hyundai/Kia, maybe even a Daewoo.....I'll stick with Cadillac.
 
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