2008 Caddie CTS Heavy Oil Usage

Status
Not open for further replies.
Joined
Jul 22, 2014
Messages
23
Location
MO
I have an 08 CTS 3.6L Non DI. It has always used oil (maybe 2 quarts in a 6500 mile change interval) between changes but at about 80k the usage increased dramatically. I am topping off a quart every 800-1000 miles. Spec is for 5W 30 synthetic which I have followed religiously. There is no sign of leak or burn at startup or when hot (I have stood in back of the car while my son revs it to 5k rpm and no smoke). I have also checked the coolant for oil contamination and it is perfect. The car runs great and has no deterioration in gas mileage or performance.

Any recommended actions? 1. Go to High Mileage Synthetic? 2. Switch to higher weight oil like 5w 40? 3. Try an additive (I don't really like that choice but respect the knowledge here).

I am going to change the plugs soon but I don't expect to necessarily find anything their either. Any advice would be greatly appreciated!
 
Last edited:
Make sure the air filter/intake is not restricted. Take a look at the throttle plate. Is it covered with oil? Can you service the PCV valve?
If you find the intake/throttle body is oily, then the oil is getting there via the crankcase ventilation system.
Look closely at the pleats in the oil filter. If you find a lot of carbon in the filter the rings may be worn allowing blow by and sludge to form in the oil.
 
Not sure about the 08's but I know on 05's the PCV valves had fixed holes in them and sometimes drilling them out a little bit would help with oil consumption. They are known oil burners though. My friends 05 CTS ran great but it was drinking oil at a rate of 1qt/1000 miles at 120k.
 
Thanks for the quick responses! I will start looking into the intake and PCV system/valve issues. The Intake has to be taken off to do the plugs so I will try to inspect all of the intake, air filter, and throttle plate/body.

Regarding the oil...why go to zero winter viscosity? Would it leave adequate film protection at startup?
 
Originally Posted By: jcbcts
Thanks for the quick responses! I will start looking into the intake and PCV system/valve issues. The Intake has to be taken off to do the plugs so I will try to inspect all of the intake, air filter, and throttle plate/body.

Regarding the oil...why go to zero winter viscosity? Would it leave adequate film protection at startup?


My money is on the PCV. Also, a 0w will not affect protection in theroy. It is better to have an easier flowing oil to make sure it gets pumped to the vital parts.
 
Originally Posted By: jcbcts


Regarding the oil...why go to zero winter viscosity? Would it leave adequate film protection at startup?
yes. A cold 0 viscosity is still very thick.
 
Originally Posted By: jcbcts

Regarding the oil...why go to zero winter viscosity? Would it leave adequate film protection at startup?


Better protection at cold start is the main reason FOR 0wXX oils. Faster pumpability, gets to the wear surfaces faster.

Hot restarts are no problem either, as its still a 30 or 40 weight oil at operating temp.
 
Originally Posted By: jcbcts
Regarding the oil...why go to zero winter viscosity? Would it leave adequate film protection at startup?


Also, despite having a zero in the description, it is not "zero winter viscosity". It only means that it meets the required specification for a 0W oil - which is hardly different than a 5W or even a 10W at anything above 0 Fahrenheit.
 
There are 2 PCV lines near the front of your plenum. Take a flat head screwdriver and pop them out gently. Spray carb/intake cleaner in the tubes and the holes they go into. Also a good time to clean the intake out as well. This can help with oil usage as those lines can get dirty and will cause higher crankcase pressures.

A high mileage oil can't hurt either. Use a regular HM oil and change sooner like 3000miles to clean the engine up and redo the PCV/Intake cleaning again before you change.

I have found doing that helps the 3.6 motors a lot. I am on my 2nd 3.6 (05 and 09 CTS) plus others like my BiLs old V6 STS and customers cars with the 3.6.
 
Originally Posted By: Rand
Was that one of the engines that stretched timing chains?


Yea the timing issue was mostly low oil caused. GMs fix was to reprogram the oil life monitor to change the oil sooner, seriously that's what the recall did. The problem was the oil chain would starve before the rest of the motor and/or oil level sensor. That was caused by people doing long drain intervals and not checking their oil level. My 1st CTS had about 60k, my BiLs STS had almost 200k, and other customers with over 100k on their chains with no problems as I kept the oil up to level and beat it over their heads to check the oil level every 1000miles or once a month.

So as long as you keep the oil level good its rare to have oil chain issues.
 
As I tell the folks over at cadillacforums.com, when you're adding that much oil you don't have to worry much about oil changes. Just keep it topped up and put in a filter every 10,000 or so.
 
Same problem with a 2006 Caddy CTS 3.6L with 52,000 miles I picked up a few months ago. Car in immaculate shape, only oil consumption a major issue. I changed all filters, cleaned the TB and MAF, installed an Elite catch can on the PCV, changed plugs and did a piston soak using AC Delco X66-P, and did a couple of Amsoil Engine Flush treatments on it. Also did a CRC Intake Valve Cleaner treatment on it for good measure. The consumption dropped dramatically. But still a lot of oil that goes thru the PCV line. The design of the PCV port and it's location looks like the staff at R&D was stoned. I also moved over to a 10w30 syn as opposed to the recommended 5w30 since the 10w30 has a much lower NOACK. At least the oil consumption trimmed down to a fraction of what it was when I got the car.
 
You are right on with the CTS issues! I have a 2008 at nearly 100k with the original timing chain. I couldn't imagine the damage to these engines when people go 8000 mile intervals and never check the oil. Then the tech doesn't mention to them that they only removed 2-3 quarts of oil and the cycle continues! I can't blame caddie owners though. You pay that kind of money you shouldn't have to pop the hood every fill up.

Anyway, thanks for the great advice on cleaning out the tubes and intake. There is no PCV valve to inspect or change so I was at a loss for what to do. Caddie forum just says put a catch can on but that doesn't stop the usage...just keeps it from reaching the combustion cycle.

What did you mean by regular "HM" oil?
 
Last edited:
Originally Posted By: jcbcts
You are right on with the CTS issues! I have a 2008 at nearly 100k with the original timing chain. I couldn't imagine the damage to these engines when people go 8000 mile intervals and never check the oil. Then the tech doesn't mention to them that they only removed 2-3 quarts of oil and the cycle continues! I can't blame caddie owners though. You pay that kind of money you shouldn't have to pop the hood every fill up.

Anyway, thanks for the great advice on cleaning out the tubes and intake. There is no PCV valve to inspect or change so I was at a loss for what to do. Caddie forum just says put a catch can on but that doesn't stop the usage...just keeps it from reaching the combustion cycle.

What did you mean by regular "HM" oil?


HM is High Mileage, HM usually means High Mileage oil on these forums. I have used Valvoline Maxlife and Castrol HM in many 3.6's with good results. Mostly 5w30 but have used 10w30 if the customer complained of oil usage.

Yea no PCV valve itself just the 2 lines, 1 on each side of the Plenum. Clean those out and that helps with oil usage on the 3.6's.
 
And, if you are going to go say Maxlife HM 10W-30 for a few shorter changes, I'd suggest a can of BG109 (now called ERP). It's a nice moderate engine cleaner for critical surfaces. Works well on loosening rings so they can build compression and control oil/blow-by.

Kreen from Kano Labs will do it faster, but it's pretty aggressive. With the BG109 it'll have the rings loosened in less than 10,000 miles and you should see a drop in oil consumption.

It's one of the non-snake-oil products that does help engines as they accumulate mileage and deposits. It will not make a motor sparkly clean inside. But it will free sticky bits that have some movement and some stiction. And I suspect that your rings are in that position ...
 
Last edited:
Took some action on my CTS this weekend. I removed the air intake hose and inspected the throttle body and plate. Both were covered in oil – not sludge but fresh oil. There is a tube that connects to the intake hose that is part of the crankcase ventilation. It was clear that it was the source of the oil – inside of it was coated with oil and it dripped from the hose when removed. I also removed and inspected the 2 ventilation hoses on the left and right sides of the intake plenum (manifold). They were clear with only minor oil residue present.
Actions I took:
1. I sprayed intake cleaner into all 3 CV hoses
2. I thoroughly cleaned the throttle body and plate with Throttle Body cleaner
3. I hooked the intake back up and warmed the car up with a short drive and then sprayed additional throttle body cleaner (about 1/3 of the can) into the intake at idle and revving to 2500rpm
4. I then poured Seafoam into all three CV hoses and let sit for 30 mins
5. I had about 2/3 can of seafoam left so I poured 1/3 into the oil and 1/3 into gas tank
I will drive for 500-1000 miles and then change the oil. I have CEL light on due to running engine with the intake disconnected – I didn’t bother clearing it with my scanner – it should go off in a day or two.
I know I said I didn’t want to pour any additives in but I figure Seafoam is petroleum based and has been around so it wouldn’t hurt anything. It should be effective though to dissolve any residue in the CVS with the direct application. I didn’t feel like I could get enough Throttle Body cleaner into the hoses to flow all the way through.

I held off on changing the spark plugs for now - car runs great and I am still a little shy of 100k.
 
Last edited:
Status
Not open for further replies.
Back
Top