: High oil consumption in 3.6L 2005 STS



holta
01-25-12, 02:06 PM
My 2005 STS (72,000 miles) consumes oil at a ridiculous rate. I've had the car for 2 months, driven ~5,000 miles and had to add 7 qts of oil. I know 1 qt every 2,000 is acceptable by GM, which to me is still outrageous. The time I had to add 4 qts, the car wouldn't start at all and didn't give me a "low oil" indication until the 3rd or 4th attempt (nothing previous to the incident). I had to disconnect the battery afterward to wipe the codes. I've driven ~1,000 miles since then and have added the other 3 qts. Is there a reasonable explanation for this? Can any repairs/maintenance be covered by a warranty or manufacture damages?

I've seen mentioned on other posts about WOT (what is this?) and piston/cylinder cleaning procedures. How much would these services cost at a dealer? I don't have the resources to do any major projects myself.

C&C
01-25-12, 02:35 PM
Well, first thing would be to try to determine how the oil is being used: leaking, burning past the rings or burning past the valves. A leak down test could determine whether the oil is being burnt from stuck oil rings or worn valve seals (obviously oil drips under the engine would be from oil leaks). The WOT or AKA, the Italian Tuneup involves taking your vehicle to a safe location (in this case a highway or road free of too much traffic) and in a lower gear, say second or third, push down on the throttle WOT (wide open throttle) to say 60 or 70 mph then release the throttle and let it coast to around 30 mph, then repeat a couple or so times. This WOT technique to to try to free up the piston rings that may have sludged up and are now not provided a good oil seal (allowing oil to reach the combustion chamber and getting burned off). Another consideration could be a PCV (positive crankcase ventilation) system that is stuck in the open position and is allowing the oil vapors to be burned off at a too rapid rate.

Saila22
01-25-12, 06:11 PM
Try Pennzoil Platinum 10w30 on your next few oil changes.

dannyquest
03-10-12, 04:51 PM
Yes, my 06 sts v6 burned 1 qt. oil every 760 miles. Cadillac installed new pistion rings. 27000miles later haven't used any oil. Danny

satchmo69
01-21-13, 08:07 PM
How much does it cost to get pistom rings replaced? I just bought an 05 sts with 37, 000 miles on it and im burning a quart every 500 miles it has a 3.6

EChas3
01-21-13, 09:02 PM
Sucks! Have you tried finding a dealer that will go to bat for you with Cadillac? Some will. (Even a free parts deal would help.)

Where are you located?

carter's_sts
01-23-13, 02:07 AM
That's crazy consumption. You should be seeing huge puddles (if leaking) or noticeable smoke out the exhaust. Unfortunately it is probably the rings.

scott9001
01-23-13, 08:19 AM
when was the last time you actually did a oil change? other than just adding fluid and did the owner before you change it? when the oil is worn out it will burn quickly quality oil goes a long way... that being said what kind of oil are you using? hopefully it doesent need rings but the best of luck to you!

KRSTS
01-23-13, 11:45 AM
How much does it cost to get pistom rings replaced? I just bought an 05 sts with 37, 000 miles on it and im burning a quart every 500 miles it has a 3.6

It IS an eight year old vehicle with an engine that is known to use oil, still with only 37000 miles it should not be using that much oil. It is unusual that the rings would be bad on that low mileage vehicle.
Your probably not burning it or you would notice smoke. More than likely it is leaking somewhere.

rleblanc
01-23-13, 01:46 PM
My 05 STS is using oil as well....about a quart/2000 miles (rouhgly). I just read above that GM considers that "normal"....not me. That is silly. Regardless, I had it checked by my dealer and it has NO leaks. I was told it's probably burning it through the rings due to some sludge, etc. There is NO noticeable smoke from the exhaust so it's not too bad. I was told they have a kit for about $50 that they can use to clean the pistons/rings out without having to take everything apart. I'll be doing that on my next oil change. I figure $50 for the kit is a cheaper option to try before tearing things apart. Ask your dealer about the kit.

curtc
01-23-13, 03:27 PM
OP, check your intake ducting as well for oil residue...It is common for the 3.6 to develop this issue...Poke around in the 1st Gen CTS forum, WAY more information regarding this unfortunately COMMON problem...There is actually a PCV modification that looks to be helping many 3.6 owners.

malatu
01-23-13, 04:23 PM
A kit? Maybe they're going to throw in a can of stp fuel treatment and charge you $50.


My 05 STS is using oil as well....about a quart/2000 miles (rouhgly). I just read above that GM considers that "normal"....not me. That is silly. Regardless, I had it checked by my dealer and it has NO leaks. I was told it's probably burning it through the rings due to some sludge, etc. There is NO noticeable smoke from the exhaust so it's not too bad. I was told they have a kit for about $50 that they can use to clean the pistons/rings out without having to take everything apart. I'll be doing that on my next oil change. I figure $50 for the kit is a cheaper option to try before tearing things apart. Ask your dealer about the kit.

curtc
01-23-13, 04:59 PM
A kit? Maybe they're going to throw in a can of stp fuel treatment and charge you $50.

Probably Chevron Techron actually....$12.99 at Advance Auto :) BOGO deals sometimes...

SC2150
01-24-13, 06:38 PM
Tons of info on here on the causes and fixes. Click on my username and find more posts until you get to the oil consupmtion threads and read. If you want help, just ask.

:thumbsup:

satchmo69
01-25-13, 10:29 PM
Oil was changed every 3, 000 miles and i use mobile 1 and changed it 2 months ago and have gone through 4 quarts. I got the car fax and they took care of this car. The thing is I bought the car fron a dealership and they said they did an oil chang. 500 miles later I hear a noise check the oil dipstick is dry. Added 4 quarts noise went a way n been dealing with this problem ever since and didnt get warranty and dealership says nothing they can do. I think they sold ne the car with no oil. Clinbed under car and there was small anount by pan never seen any leak on ground. But its definately coning out the exhaust

carter's_sts
01-26-13, 12:53 AM
I wonder if they under filled the oil after the change and you unknowingly did the damage. Something went way wrong. That's way more consumption than I've read others talking about on here.

I would keep pushing them to do something for you even if they don't have to. Escalate it up the chain and make a lot of noise. It might work.

malatu
01-26-13, 08:28 AM
Oil was changed every 3, 000 miles and i use mobile 1 and changed it 2 months ago and have gone through 4 quarts. I got the car fax and they took care of this car. The thing is I bought the car fron a dealership and they said they did an oil chang. 500 miles later I hear a noise check the oil dipstick is dry. Added 4 quarts noise went a way n been dealing with this problem ever since and didnt get warranty and dealership says nothing they can do. I think they sold ne the car with no oil. Clinbed under car and there was small anount by pan never seen any leak on ground. But its definately coning out the exhaust

I haven't looked at a carfax in a while. When did they start reflecting the maintenance record of a car?

SC2150
01-26-13, 09:53 AM
C&C posted good info here.

These cars you MUST check oil every few fill ups.

The piston ring buildup is caused by the oil ingestion through the dirty side of the PCV and a good (most let as much through as they catch) oil separating catchcan will stop the ingestion. But then there are 3 issues. If a DI motor the valves will need to be cleaned somehow and damage to the valve guides may have occured as well due to this hard coking buildup as it is very abrasive:
http://i262.photobucket.com/albums/ii115/RevXtreme1/LLTvalves4.gif
http://i262.photobucket.com/albums/ii115/RevXtreme1/LLTvalves1.gif

Then, once the ingestion has been stopped the rings are what need to be freed up. Look close at how the oil deposits (gunk) build up so the rings cannot move freely and seal properly....(read C&C's post for explanation) they may free up after a few thousand miles of runnung w/a proper oil separating system installed and some hard WOT runs seem to help this (this piston was damaged while a tuner disabled the know sensors):
http://i262.photobucket.com/albums/ii115/RevXtreme1/Pistonringlifted-1.jpg

Notice how the oil ring (bottom most) that controlls the oil from getting sucked into the combustion chamber is gunked up and cannot move freely to seal properly as well as the scraper (second ring) and the compression (top ring) also cannot move freely.

If this does not work, then yes, a disasembly and new rings and cross hatch hone is required...not s cheap or easy job.

Upper induction cleaning will loosen some of the valve deposits and buildup on the piston tops and combustion chamber, but this should be done only once in a while (try it after installing the oil separating system) as when the hard deposits break loose, some are forced past the rings and cause scouring to the pistons and cylinder walss. (Some minor scouring is not an issue, but do this to often and the scour marks become to deep compromising the ability for it to ever seal properly):
http://i262.photobucket.com/albums/ii115/RevXtreme1/pistonringlandgunk003.jpg

Again, do NOT assume your oil level is fine...check it every few fill ups and get to know how much your motor is consuming. Oil is cheap, and the life blood of your engine....chek it often!!!!! It is hard for any of us born in the 40's-50's-60's to imagine some one not checking engine oil regularly and all fluid levels.....but today the manufacturer wants you to rely on the service center to do all as this creates a reacurring revenue stream, as most vehicles dont even come with a trans fluid dipstick allowing you, the owner to maintain your car.

:thumbsup:
http://i262.photobucket.com/albums/ii115/RevXtreme1/Pistonringlifted-1.jpg

gep
03-09-17, 01:52 PM
I have a 2007 sts 3.6 L it just started to use oil bad, like 1 quart in 500 trip miles i inspected the PCV system and only found 1 PCV on the right side of the engine. The left side has none. The oil is being sucked up on the left going in the air tube that means it will go thru the throttle body. On the left is a tube with no valve going from the tapped cover rear to the air tube in the front. I went to the dealer that serviced the car when needed it is not a cadillac dealer its a chevy dealer. i pointed out all the service bulletins there answer was sorry out of warranty on the other hand they want me to buy a $ 50,000.00 truck ha ha
I am tempted to go straight to cadillac to the service management. What do you all think about that. On the other hand i was thinking of adding a PCV valve on the left side.
Thanks

Vraatzii
03-09-17, 11:27 PM
There are many threads on this ,also in the cts side. They tell you how to modify the pcv system and add a catch can to reduce oil consumption.Also how to clean out the build up. This is a common problem for 3.6 engines.

taviarose
03-22-17, 01:35 PM
Check for oil in your spark plug wells first. I was losing oil by the time I go to my next oil change it was empty and I had no idea because everyone kept saying there were no leaks..never saw oil on the ground. It was my valve cover gaskets.

curtc
03-22-17, 02:08 PM
I was losing oil by the time I go to my next oil change it was empty and I had no idea because everyone kept saying there were no leaks..never saw oil on the ground.

Did you ever think to check the oil level between changes? Guess I was taught to check it periodically as part of owning a car....

Hoosha61
03-23-17, 04:16 AM
Bought my 2010 STS 3.6 this past summer. I've only put about 3,400 miles on her and just added my first qt of oil. I Usually check level every other fill up. From what I'm reading I'm one of the lucky ones.

KRDCAD
03-23-17, 09:19 AM
Bought my 2010 STS 3.6 this past summer. I've only put about 3,400 miles on her and just added my first qt of oil. I Usually check level every other fill up. From what I'm reading I'm one of the lucky ones.
You don't have to worry about high oil consumption in the 3.6L DI (post 2007) engines.

curtc
03-23-17, 09:29 AM
You don't have to worry about high oil consumption in the 3.6L DI (post 2007) engines.

I call BS...PCV orifice wasn't redesigned until the LFX redesign, STS never got the LFX, only LLT...Check the 2nd gen CTS forum....LOTS of oil consumption and timing chain threads....LY7/LLT = CHECK YOUR OIL!

KRDCAD
03-23-17, 04:35 PM
Always check your oi frequently on all engines. The Northstar leaks like a sieve

curtc
03-23-17, 04:49 PM
Always check your oi frequently on all engines. The Northstar leaks like a sieve

I completely agree with that statement. Oil level should be checked on a regular basis on any engine. But your statement regarding the 08+ DI 3.6 not having the same oil consumption issues as its LY7 predecessor is flat wrong. Not saying every single 3.6 guzzles oil but there's enough evidence out there to say it's a likely scenario that should be monitored. I know I'll never own another GM 3.6 of any flavor.

KRDCAD
03-23-17, 05:22 PM
I had an 08 STS with the 3.6 DI for eight years and over 80K miles. Never had to add a drop of oil between oil changes every 5K miles. Just my experience. Haven't seen many reports over the years on this forum about high oil consumption in that engine either.

Ludacrisvp
03-23-17, 06:29 PM
Always check your oi frequently on all engines. The Northstar leaks like a sieve

Across 3 northstars (2004 and newer) none of them have leaked like you seem to suggest.

My 02 Deville DTS did have some leaks (at least according to the dealer) but it never had any evidence of one on the ground under the car in the garage.