Excessive Oil Consumption?

[LJ Hawkeye]

Background:
2001 Corvette coupe ordered from the factory through a local dealer with delivery in November, 2000. Almost since taking possession the car appeared to be using oil - roughly 1 qt. every 1,500 to 2,000 miles. I wasn’t that concerned, since I assumed that was typical for that model (my previous vette was an '87). I mentioned it several times to the dealer, but was always told that was normal. At 27,320, dealer did an oil change and began an oil consumption test. I monitored the consumption, with the following results:
• 28,332 (1,012 miles) - 1 qt
• 29,373 (1,041 miles) - 1 qt
• 30,598 (1,225 miles) - 1 qt
• 31,371 (776 miles) - 2 qts

Each time I added oil, I was told that the consumption was "normal.” Since then, I have continued to monitor the consumption, but haven't kept track. Eventually I advised dealer who suggested another oil consumption test. I was not told to bring the car in after an oil change to have the drain plug sealed, just to change the oil and filter and monitor the usage.
• 37,652 - oil changed with new filter
• 38,459 (807 miles) - 1 qt
• 38,865 (406 miles) - 2 qts
• 39,200 (741 miles) - 1 qt
• 40,259 (1,059 miles) - 1 qt
• 41,205 (946 miles) - 2 qts
• 42,325 (1,120 miles) - 1 qt
• 43,209 (884 miles) - 2 qts

Service rep advised that another oil consumption test needed to be done. None of the previous oil consumption could be documented, since they hadn't sealed the drain plug (now he tells me).
• 43,923 - oil change done and oil consumption test begun by having dealer seal drain plug.
• 45,075 (1,152 miles) - 1+ qts

Called service rep and he advised to bring in for confirmation and oil replacement. Service rep checked oil level, added 1 quart and said he would check with the extended warranty company.
Service rep called to tell me the extended warranty company felt the oil consumption was “within normal limits.” They further explained that (I’m paraphrasing), if I wanted to, dealer could explore further by opening up the engine for a physical inspection. They would only pay for that inspection if actual damage was found to the internal engine parts that would be covered under the extended warranty. Service rep advised that the inspection process could cost as much as $2,000 to $3,000, which I would have to pay for. I decided to continue monitoring the oil consumption. Continued to check the oil on a weekly basis.
• 46,278 (1,150 miles) 1+ qts

Called service rep on to advise. He said he would add this info to the record. He advised to add a quart and continue to monitor. No need to bring the car in for confirmation.
• 46,829 (551 miles) 1 qt.

Called service rep to advise. He said he would add this latest information to his records and to call the next time I showed a quart low. At that time he would check with the extended warranty company again.
• 48,053 current mileage (1,224 miles) - 1 qt

I apologize for the lengthy detailed history, but I wanted everyone to have all the information. My question is this: Does anyone have any information that I could use to pass on to the dealer and ultimately the extended warranty company to show that something is wrong and warrants further diagnostics, but not at my expense?

Thanks in advance.

LJ Hawkeye

 

[TODD L GRIFFITH]

There is a problem with excessive oil getting passed the PCV valve into the intake manifold. To check this oil usage issue, I would remove your air intake duct, hold the throttlebody butterfly open and shine a flashlight in and look for evidence of excessive oil inside the intake manifold. I have a hunch this could be your oil usage problem. If this is the case, the fix is to install an oil catch can. The catch can will trap 99% of the oil heading for your intake manifold, intake ports and combustion chambers. http://cgi.ebay.com/ebaymotors/Oil-...oryZ6778QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
This oil catch can will work on a Corvette also, not only a 240SX. All you need to do is intercept the oil valley tube on its way to the PCV valve, place it on the can inlet and plug the tube going into the PCV valve on the can discharge. The can will be inline before the PCV valve, it's that easy. The can mounts to the passenger side cylinder head in front using the brackets shown with the can needing little modification. I like the cans with the side mounted sight glass, so you can monitor the oil level in the catch can. It's better for oil going into the catch can, then through your intake ports to be burnt during combustion. The oil trapped in the can should be drained and not reused. All you will need to do is maintain your level on the dipstick with new. You will be using oil instead of burning it. I'm draining quite a bit of oil out of mine each month. After many, many modifications to the PCV valve/system GM ended up eliminating it on the C5 in 2004 from what I've heard. The 01' ZO6 had ring seal problems, and I think it was limited to the LS6. Maybe someone else will chime in with more information regarding the 01' LS1 and that issue.
Here is what the manufacturer says about the catch can:

The oil catch tank mounts above your valve cover and ensures excess oil and dirt does not get inside your engine. This will ensure better mileage and better performance on your engine.

Ain't that the truth!!

 

[LJ Hawkeye]

There is a problem with excessive oil getting passed the PCV valve into the intake manifold. To check this oil usage issue, I would remove your air intake duct, hold the throttlebody butterfly open and shine a flashlight in and look for evidence of excessive oil inside the intake manifold. I have a hunch this could be your oil usage problem. If this is the case, the fix is to install an oil catch can. The catch can will trap 99% of the oil heading for your intake manifold, intake ports and combustion chambers. http://cgi.ebay.com/ebaymotors/Oil-...oryZ6778QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
This oil catch can will work on a Corvette also, not only a 240SX. All you need to do is intercept the oil valley tube on its way to the PCV valve, place it on the can inlet and plug the tube going into the PCV valve on the can discharge. The can will be inline before the PCV valve, it's that easy. The can mounts to the passenger side cylinder head in front using the brackets shown with the can needing little modification. I like the cans with the side mounted sight glass, so you can monitor the oil level in the catch can. It's better for oil going into the catch can, then through your intake ports to be burnt during combustion. The oil trapped in the can should be drained and not reused. All you will need to do is maintain your level on the dipstick with new. You will be using oil instead of burning it. I'm draining quite a bit of oil out of mine each month. After many, many modifications to the PCV valve/system GM ended up eliminating it on the C5 in 2004 from what I've heard. The 01' ZO6 had ring seal problems, and I think it was limited to the LS6. Maybe someone else will chime in with more information regarding the 01' LS1 and that issue.
Here is what the manufacturer says about the catch can:

The oil catch tank mounts above your valve cover and ensures excess oil and dirt does not get inside your engine. This will ensure better mileage and better performance on your engine.

Ain't that the truth!!

Thanks for your suggestion, but being that I am non-gearhead with virtually no mechanic skills, I have no idea what you've just said. Keep in mind, I'm not aware of any excessive burning of oil (blue smoke from the exhaust), I only know that the engine is consuming more oil than what I feel is normal. From what I understand from your suggestion, it does not resolve the excessive usage, but only traps it to be disposed of. I'm looking for a solution that will resolve the excessive usage, if that is possible.

Thanks again.

LJ Hawkeye

 

[TODD L GRIFFITH]

Thanks for your suggestion, but being that I am non-gearhead with virtually no mechanic skills, I have no idea what you've just said. Keep in mind, I'm not aware of any excessive burning of oil (blue smoke from the exhaust), I only know that the engine is consuming more oil than what I feel is normal. From what I understand from your suggestion, it does not resolve the excessive usage, but only traps it to be disposed of. I'm looking for a solution that will resolve the excessive usage, if that is possible.

Thanks again.

LJ Hawkeye

The oil has to be going somewhere. If you are not burning it, then it must be leaking on the ground instead. If not, then you must be burning it, it has no other place to go. Blue smoke, well something less noticable over time I'd say sounds about right. Hopefully you will get it resolved.

 

[TODD L GRIFFITH]

Hey LJ,
Read this thread from the CAC C6 forum. http://www.corvetteactioncenter.com/forums/showthread.php?t=96524

This is what I'm talking about.

 

[gmjunkie]

Background:
2001 Corvette coupe ordered from the factory through a local dealer with delivery in November, 2000. Almost since taking possession the car appeared to be using oil - roughly 1 qt. every 1,500 to 2,000 miles. I wasn’t that concerned, since I assumed that was typical for that model (my previous vette was an '87). I mentioned it several times to the dealer, but was always told that was normal. At 27,320, dealer did an oil change and began an oil consumption test. I monitored the consumption, with the following results:
• 28,332 (1,012 miles) - 1 qt
• 29,373 (1,041 miles) - 1 qt
• 30,598 (1,225 miles) - 1 qt
• 31,371 (776 miles) - 2 qts

Each time I added oil, I was told that the consumption was "normal.” Since then, I have continued to monitor the consumption, but haven't kept track. Eventually I advised dealer who suggested another oil consumption test. I was not told to bring the car in after an oil change to have the drain plug sealed, just to change the oil and filter and monitor the usage.
• 37,652 - oil changed with new filter
• 38,459 (807 miles) - 1 qt
• 38,865 (406 miles) - 2 qts
• 39,200 (741 miles) - 1 qt
• 40,259 (1,059 miles) - 1 qt
• 41,205 (946 miles) - 2 qts
• 42,325 (1,120 miles) - 1 qt
• 43,209 (884 miles) - 2 qts

Service rep advised that another oil consumption test needed to be done. None of the previous oil consumption could be documented, since they hadn't sealed the drain plug (now he tells me).
• 43,923 - oil change done and oil consumption test begun by having dealer seal drain plug.
• 45,075 (1,152 miles) - 1+ qts

Called service rep and he advised to bring in for confirmation and oil replacement. Service rep checked oil level, added 1 quart and said he would check with the extended warranty company.
Service rep called to tell me the extended warranty company felt the oil consumption was “within normal limits.” They further explained that (I’m paraphrasing), if I wanted to, dealer could explore further by opening up the engine for a physical inspection. They would only pay for that inspection if actual damage was found to the internal engine parts that would be covered under the extended warranty. Service rep advised that the inspection process could cost as much as $2,000 to $3,000, which I would have to pay for. I decided to continue monitoring the oil consumption. Continued to check the oil on a weekly basis.
• 46,278 (1,150 miles) 1+ qts

Called service rep on to advise. He said he would add this info to the record. He advised to add a quart and continue to monitor. No need to bring the car in for confirmation.
• 46,829 (551 miles) 1 qt.

Called service rep to advise. He said he would add this latest information to his records and to call the next time I showed a quart low. At that time he would check with the extended warranty company again.
• 48,053 current mileage (1,224 miles) - 1 qt

I apologize for the lengthy detailed history, but I wanted everyone to have all the information. My question is this: Does anyone have any information that I could use to pass on to the dealer and ultimately the extended warranty company to show that something is wrong and warrants further diagnostics, but not at my expense?

Thanks in advance.

LJ Hawkeye

Well in my book,that is Purdy Excessive!!!!:W

 

[WNH]

The oil has to be going somewhere. If you are not burning it, then it must be leaking on the ground instead. If not, then you must be burning it, it has no other place to go. Blue smoke,.

Blue Smoke. If its burning that much oil, you would probably see blue smoke.

 

[TODD L GRIFFITH]

Blue Smoke. If its burning that much oil, you would probably see blue smoke.

You are probably going to see some smoke burning a quart every 1200 miles I agree. LJ indicated that there wasn't much if any blue smoke, but there has to be some smoke associated anyhow.

 

[wishuwerehere82]

I burn 1 qt. every 10,000 miles in my 98. I thought that was a lot.

 

[gmjunkie]

You are probably going to see some smoke burning a quart every 1200 miles I agree. LJ indicated that there wasn't much if any blue smoke, but there has to be some smoke associated anyhow.

Synthetic Oil doesn't smoke near as bad as Petroleum Oils!!It will blow oil out the tail pipes before it will smoke much!!!

 

[Pac-man]

Burned oil in my first C5 Vette,1qt every 500, no smoke. I never made a big deal about it, just added oil when needed. Car ran great so did'nt care. Some burn oil some do'nt. Some more than others. If it's running great I woud'nt let someone tear my engine down. It's known lots of C5's burn oil.

 

[schmaltzr]

I'm no mechanic, but I have some experience in analyzing problems. It seems to me that the oil either has to leak out or be burned out the exhaust. If it is leaking out you would see it on the outside of the engine or underneith the car after you drive it. You might even see a few oil drops.

Lets say that you don't see oil drops. That means that the oil is going out the tail pipe either in vapor or burned by the catalytic converter. There are only a couple ways that the oil will be pumped out:

Oil blow by past the piston rings
Positive Crank Case Ventalation defect
Valve guide seal leakage.

If there is blow-by then I would suspect that the compression is also diminished since it means that the rings are letting the oil by as well as the air/fuel mixture. This would also make your oil smell gassy. A compression test may tell you all you would need to know.

If it is the PCV (I don't call it the PCV Valve since the 'V' stands for valve and would be reduntant) , you may need to replace the PCV. Sometimes they stick open when they have a few miles on them and they allow way too much oil past them. I tore a PCV apart from my Toyota one time and all it contained was a plastic chamber with a small steel ball about 1/4 of an inch around. The ball acts like a one way valve for the crank case ventilation.

I'm not aware of any way to determine valve guide seal leakage without physical examination. From what I remember on other cars there is a rubber seal around the valve stem in the upper head near the rocker arms. I'm assuming that the LSx engines still use these same kind of seals. It used to be that over time the rubber would deteriorate and crack allowing the oil to be sucked in the intake and or blown out the exhaust. Tearing the engine down doesn't seem necessary to me to find out where the leak is after all what are they looking for? They may find scoring on a cylinder wall (Compression Test will tell you that it is scored/defective}, a ring may be broken (again compression test) or possibly a head gasket leak in the right area that allows oil to be pulled into the exhaust if there is a pressurized oil passage that has been compromised. These are just thoughts - Ron

 

[TODD L GRIFFITH]

Nice post Ron. That's basically the way I see it.
As I said, I have the catch can installed. The can has clear tubes running from the oil valley tube to the can, then out to the PCV valve. At idle, I have seen oil in the tube travel from the main oil gallery (valley tube) into the can. Without the can, you can see that it would be pulled right through the PCV directly into the intake. This is not only oil, at start up when the engine temperature hasn't reached 140 degrees, you are still condensing inside the motor. I've also seen moisture being pulled up the tube also. A nice mixture for sure. My thinking has been the cars that have it the worst are the ones that don't quite get driven long enough, whether it is a short commute, or something to grab groceries in. The oil/coolant temperatures are not hot enough, long enough to burn off all the moisture in the oil.
Don't let the car warm up in the driveway too long without having a catch can installed if you live in a cold climate. :L

 

[1KLRTOY]

My 01 used oil the same as yours, I let it go not wanting to have the dealer tear the engine apart,I tried most everything ,an AMW catch can the updated pcv, 10-30 oil nothing worked and mine is an A4, after a 9 mo. oil consumption test at 53k GMPP agreed to do the repairs. They replaced the oil and #2 compression rings and now it uses no oil (less than 1/2 qt. @5k) and runs 100% better. If your 01 is using oil theres only one way to fix it, rings! nothing else will fix it. My only regret was waiting so long to have it repaired

 

[zagger]

The oil is either ingested by the engine or it is spilled out of the motor. Oil filter or valve covers are common places for oil to leak. I would assume the car was lifted and thoroughly inspected from the bottom. Still I would start by steam cleaning entire engine. After a week or two of driving I would check to see if there are any evidence of a small leak anywhere. While driving I would also keep track of oil pressure. Low readings could indicate excessive bearing clearances or otherwise worn engine. A compression check would be the next step, not an easy job on a C5. If these tests show no cause for oil loss then replace the PVC (will not be redundant and call it a valve second time:L) and drive it as normal and keep adding oil. Good luck with finding the cause.

 

[c4c5specialist]

HI there,
1 Quart in 2000 miles is considered normal, by GM per TSB 01-06-01-011D.
Anything more then that, a consumption test should be done, per your post.
PCV, NO!
Lets get back to driving style, are you consistantly about 3500 rpm for extended periods of time?
Do you enjoy reving the engine and accelerating hard???
If so, you most likely are having blowby past the rings, per TSB 01-06-01-023A.
Because you are NOT LS6, the valley cover in this bulletin would not apply, but the piston rings would.
You will NOT see any actual failed parts, so if that is what your extended warranty is looking for, your kind of out of luck.
These bulletins have been out for a long time, and I cant believe someone would tell you its normal, ITS NOT!!
Step one, compression test.
Step two, if they are all even and up around the 160 psi mark, you ruled out actual engine component failure. And need to press this with your dealership.
Allthebest, c4c5

 

[tankman]

I just had the Oil Consumption test done to my 03 caddy with a Northstar. It was consistently around 2qts every 1,000 miles. Without hesitation my dealer scheduled an engine rebuild for me.
I was really impressed with GM's willingness to give me an engine rebuild.

Although even going through that much oil I have never seen any clouds of oil, and never a drip.

Good luck with your Vette

-Eric

 

[c4c5specialist]

HI there,
Thats true, what most people dont realize is that the catalytic converters are SO EFFICIENT, that you will NEVER see smoke.
Once there are at operating temperature, they just catalyze the hydrocarbons too well.
Allthebest, c4c5