: Major engine/oil problems

02-26-09, 07:03 PM
I have a 2005 STS with 59,000 miles. Last week my engine started bucking and knocking and the check engine light came on. I took the car right to the dealer. When they started working on it they stated that the oil was 3 qts low causing a problem with the VVT. I change my oil @ 15% on the OLM. They changed the oil and cleared the codes. This fixed the major engin knock but now I have a engine knock at 1,000-1,500 RPM. The dealer and GM are saying it is from me not taking care of the car and changing the oil. I changed it everytime the OLM was 15-20%. Now GM will not do anything to help and the dealer here sucks. Any thoughts on why i would loose this much oil with no leak and what is the knocking issue. The car also surges between 40-45 mph.

02-26-09, 09:13 PM
Unfortunately, the OLM doesn't monitor oil level. You have no warranty of any kind? It's a shame that cars as sophisticated as these don't alert the driver when the oil drops below 1 quart low. It's a terrible way to learn that the book does say to check the oil level.

Have you already spoken with the Cadillac zone rep? Click & Clack say these are magic words, "I'm in trouble and only you can help." (I may be a dinosaur but a woman's tears still work on me.) Maybe you can get some help on a replacement from an auto-recycler. Rebuilding a N* is costly.

02-26-09, 11:35 PM
The owner's manual does say to check the oil frequently. I always check frequently with any new vehicle until I know its drinking habits.

I had a '96 STS with Northstar that burned oil. It would warn me when the oil level was about 1.5 Qt low. I'd be surprised if they have dropped that feature. Regardless, if they believe low oil was the cause of your problem, they could be withing their rights to deny a warranty claim. It's not as if GM has a lot of money to be nice any more.

02-27-09, 07:15 AM
Your STS does have an oil level monitor. I have never tested mine, but I am sure the DIC would give you a warning when the level got too low and would cause a problem with the engine. Has your car always used oil or did it just start using oil? I find that mine does not use any oil between changes, the last one was after about 10,000 miles when the DIC was at 15%.

02-27-09, 08:14 AM
Page 3-81 of my owner's manual:

This message will display when the oil level is low. See Engine Oil on page 5-18 for more information on checking your engine oil.

02-27-09, 09:57 AM
I stand corrected. I check our cars about once a month & before trips over 100 miles.

MDSTS - If the car's oil level sensor is faulty, you may have a persuasive argument to use with the zone rep. for help with the problem.

04-22-09, 08:55 AM
I have a 2005 with v6 and 55000 miles. Twice now I encountered a knocking or grinding noise from the engine, checked the oil and was at least 2 quarts down. Put oil in and the noise went away. Also had some surging at 40 - 50 mph, now that I read this thread I noticed that is gone too. I am around 15% left on the oil life in the computer. No warnings or anything came up for me either.

04-22-09, 10:34 AM
the accepted rate of oil consumption under gm guidlines is 1qt in 2000 miles, this vehicle has a tsb to replace piston rings and valve guide seals. you do have a low oil life monitor but problems show up before you get the message

04-22-09, 05:03 PM
problem with the check oil level warning is that its popping on the DIC only when the key is at the "on" position engine not running. You'll have to wait about 10 secs to wait til it can display. (i tested mine while doing an oil change).

Also, with some experiment, I found out that the check oil level shows up when you have between 2.5-2.8 liters left in the sump. The 3.6l v6 has a oil capacity of 5.7 liters so when its half, the check oil level shows up BUT ONLY when the engine is not running! Thats sad from gm...

What I do now is written in the owner manual: check oil level with the oilstick everytime I put fuel in the car. I know that just after putting gas in the car and I check the oil level, there's approx 500ml missing because the oil did not have enough time to entirely return in the sump. When its about 500ml below the add mark when the engine has just stopped, I have to add 1 qt of oil. If I wait aprrox an hour after I stopped the car, I have the accurate level.

04-23-09, 09:05 PM
Bizzare, I do my own oil changes on my N* every 8,000 miles and fill it with 8qts everytime, and when I do my next oil change, 8qts gets removed. Just did my last oil change a few days ago at 51,000 miles. Something does not sound right. If your car was burning that much oil, the catalytic convertors would be plugged and black smoke would probably pour from the tailpipes. Sure you filled it last with the proper volume?

04-23-09, 09:46 PM
Anybody that owns a vehicle and drive it daily should know the oil consumption rate iust as well as you know the gas mileage. Should not have to rely on an oil level indicator light to tell you to add oil. The only time you should have to rely on the indicator is when something out of the ordinary is going on.
The DIC WILL give you a warning while driving if the oil gets low......

12-26-12, 08:54 PM
Hey my car has 94,000 miles on it...I had the oil changed at 86,000 miles and drove home and was going to get an oil change. My car started making a noise that stopped when I drove. I checked the oil and added two quarts,,,yet when I drove home (450miles) all the oil was gone. I never had the oil indicator light come on..

12-26-12, 11:03 PM
The STS V6 does not have a low oil level warning. The V8's oil level warning is so late that it might as well say, 'You have just oil-starved your N*'.

Fortunately, the V8 doesn't generally suffer from catastrophic oil loss. Those that use oil, do so slowly and there's 8 quarts, anyway. Unfortunately, several members report their V6's had done so, with little warning.

12-27-12, 02:02 PM
According to Alldata.com only the 4,4 SC Northstar has an oil level sensor. It's combined with a oil temperature sensor.

12-27-12, 05:52 PM
Most cars have a low oil pressure warning, not the actual level. Not sure about these cars , but it is kind of hard to tell the level of oil while the engine is running. If pressure is low, the most likely cause is not enough oil.

12-27-12, 06:27 PM
According to Alldata.com only the 4,4 SC Northstar has an oil level sensor. It's combined with a oil temperature sensor.

Sure, I may be wrong. Any of us can post anything. I just remember reading a post from a credible forum member. It wouldn't surprise me at all if it varies by year & options.

Anyone else care to comment?

12-27-12, 07:24 PM
Pretty sure the 3.6 has an oil pressure sensor, I would think it would've tripped if the engine was that low on oil...

Also pretty sure the N* does too as I recall seeing a red oil can dummy light during the startup IPC self test.

12-27-12, 11:57 PM
I generally check the oil level at every fill up. So far (knock on wood) the oil level has not changed between oil changes. Although now that I typed that it will probably start burning a lot of oil.


12-28-12, 10:31 PM
'06 V6 STS, 73k miles.

I burn through a quart every 1000 miles or so. I check at every fill up because I notice that sometimes it sneaks up on me - as to say that it doesn't consume the oil at a consistent pattern. It's annoying as hell. $7 for a quart of oil every month is somewhat costly. Though new timing chains are even more costly. I'm doing whatever I can to prevent that.

12-29-12, 02:47 AM
Common in the 3.6

There is a solution, somewhere in the 1st gen CTS forum, you can dig it up.

Believe it has to do with drilling out the PCV orifice.

Cadillac Cust Svc
12-29-12, 06:56 PM
The accepted rate of oil consumption for your engine is 0.946 liter (1 qt) in 3200 km (2000 mi). Have you had this evaluated by a dealership at all? If you wanted to do that, please let us know and we'll help you get started on an oil consumption test.

Sarah (Assisting Katie), Cadillac Customer Service