: where has all my oil gone?

03-16-11, 10:01 PM
I have a 06 3.6 that i've driven for about 5 months. We recently went on a 1000 mile one way trip so i changed the oil before we left. After being back for a few weeks now, i noticed an occasional soft grinding sound last week which culminated in shuddering and more consistent grinding sound. No lights or warning messages popped up. I popped the hood and checked the oil out of habit and the dipstick didn't reach the oil! after getting my stomach off the floor i topped it off and found it to be about 3 quarts low.

i'm really curious as to where that oil went. i put the required 6 quarts in when i changed it, it hasn't been smoking or running poorly (actually got the best mileage ever out of the last tank), and the bottom of the car is clean and there isn't any oil drips on the garage floor. i do know that i drove it about 3 thousand miles before this oil change and there was at least 5-6 quarts that came out that time.

could 1000 miles nonstop in -10 to -20 degree weather eat up that much oil or is there any common things that eat oil in these engines?

is there anything i need to look out for now? i'm assuming the grinding was the oil pump sucking air but i'm not sure what the shudder was. the engine seems fine but i'm worried the whole thing is going to seize up now.

03-16-11, 10:42 PM
You have the problem! Oil is being burned up when passing thru the converters. Sound you were hearing likely was the timing chains. Caused by poor rings possibly damaged by debris coming in the air intake if not secured correctly. Gm will not do much for you. Get used to checking your oil EVERY fillup and keep a few qts in the trunk.

03-17-11, 12:46 AM
Are you sure you put the required amout of oil back in the engine???? It happens.

03-17-11, 08:16 AM
yes i put 6 quarts in and i rechecked the level after letting it idle, so i know it was full.

03-17-11, 09:13 AM
When you run that engine low on oil, it chews up the timing chains

03-17-11, 09:18 AM
3.6s drink oil period, its that simple.

03-17-11, 02:13 PM
Must be like the FWD Northstar engines. They were designed to use some oil to prevent wear.

03-17-11, 04:26 PM
i don't understand why it was fine the previous oil change and now it's all of a sudden a 2 stroke? now there is an engine speed dependent high pitched squeal now that sounds like it could be the AC compressor.

03-17-11, 04:35 PM
Sounds like you may be about to lose your timing chains and possibly the engine. I would get it t a dealer ASAP.

03-17-11, 06:50 PM
3.6s drink oil period, its that simple.

It is not simple and it is also not true. There are different 3.6L engines and the 3.6L 302 HP direct injection engine uses very little oil.

03-17-11, 08:18 PM
Unfortunately, it sounds like you developed a problem on your trip or weren't aware of a pre-existing condition. Some of the V6's do use oil but many don't. Those that do often develop timing chain issues. What's more, there was a run of bad chains, too. I hope you have a warranty. Good luck, too.

Low oil levels can reduce fuel consumption and increase power by reducing drag. Dry sumps are found in racing engines for that reason.

vintage one
03-17-11, 08:27 PM
My 07 is going into the dealer for this problem on Tuesday. I am using a quart every 1,000 miles. The dealer told me about a consumption guidleline online regarding oil loss. ultimately it could result in the replacement of the rings and valve seals.

03-17-11, 08:49 PM
I had a 2004 CTS 3.6, bought it with 9k on the odo. Never used a drop of oil for 5 years, averaging 20k/yr. Some where right around 100k I was turning a corner from a stop and merging into 45mph traffic and was getting on it a little when I heard a blood curdling grinding sound from the front.

I turned around and feathered it a couple of miles home, checked the oil and nothing! Added a quart.. nothing, added another... nothing, added 3 more before it showed up on the stick. My buddy told me that noise was the timing chains stretching and destroying themselves and that I should get them replaced soon.

I didn't. I kept checking the oil once a week or so and usually had to add a half a qt. Sometimes more, some times less. Ran fine up to 135k when I crashed it and it went to CTS heaven. It probably became an organ donor!

03-17-11, 09:42 PM
I'm surprised that the oil level was that low and the "Check Oil Message" hadn't displayed on the DIC...assuming the CTS has a DIC that is. On my 2000 STS the message would come on at 2 quarts low.

03-17-11, 10:55 PM
I honestly don't understand any reason not to have a warning at 1 quart low. Why only alert the driver AFTER the damage has begun?

03-18-11, 02:02 AM
I think the Northstar holds extra oil for cooling purposes in case of a coolant loss situation. I don't believe the motor needs almost 8 quarts just for lubrication.