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Hey guys, i'm in a real predicament... Just found out my '04 GXP is losing oil through the exhaust and I'm not real sure what I wanna do. The seep is pretty slow (for now) as it took about 6k miles using mobil 1 high mileage synthetic oil for me to find out that it is indeed disappearing. I know its very expensive to fix oil leaks in these N*, money which I dont really have right now, and i've been told by a few knowledgeable ppl that I should trade it in before it gets bad. Problem is, I really like this car. Talked to my mechanic and he recommended trying AT-205 re-seal. Have any of you used this stuff before? Did it work? I can use any advice or knowledge on the topic as I would like to figure out my options.

Thanks for the help.

Personally from what I have read/heard. I would not put any "sealers" in the engine as they just good up the engine and CAN cause oil passage blockages and other problems. Not saying that will happen but it's a possibility.

Not sure exactly about the stuff you are talking about though.


How many miles on your car?

94SilverSSEi wrote:Personally from what I have read/heard. I would not put any "sealers" in the engine as they just good up the engine and CAN cause oil passage blockages and other problems. Not saying that will happen but it's a possibility.

Not sure exactly about the stuff you are talking about though.


How many miles on your car?

I got just over 83k on the car. Everything else seems fine, only reason I know I'm losing oil is because the DIC warning light came on and when I checked it, it was down to close to 2 quarts. Not sure if its worth keeping and repairing or trading it in.

How do you know you're losing it through the exhaust?

It can only get into the cylinders and exhaust through either bad rings, a bad valve seal(s), or leaking in through the intake, which is highly unlikely.

^ Or carbon buildup, or no problem at all.

Some people's Northstars are known to consume oil and this is NORMAL. It is an engine with performance put in mind and many perfectly healthy motors will do it for many miles without issue. Another problem here is that you haven't checked your oil level for 6,000 miles? I would expect many cars to be down at least a quart at this point and still be normal. Mine doesn't really consume at this rate, but I definitely find myself occasionally topping up a bit towards the end of my change interval (5k miles).

Is your engine normal? I don't know. But it could very well be.

No matter how well maintained, these engines will leak and consume oil. I've replaced the vc gaskets, main seal and oil cooler lines, yet I still lose up to a quart every 6-8k.

You have a lot of life left in that motor so don't be too worried about oil loss. Just do a check of the oil level every fill up and top up accordingly.

Cheers.

Thanks a lot for the advice guys. After doing some research on my own and talking to both a caddy and Pontiac/GMC/Buick dealership, I came to the realization and a better understanding of all the things you guys brought to my attention. I didn't realize that the N* was "engineered" to have some oil consumption and that it is completely normal. I also didn't know that this engine performed better with conventional oil. I currently have Mobil 1 high mileage synthetic oil in it (hence the 6k miles before my last oil change), but I think from now on, I'll be using just conventional oil and changing it around every 3k.

Thanks again for the help guys. I'm looking forward to driving my GXP for many, many more miles.

And while on the topic, a pretty interesting read:

http://www.cadillacforums.com/forums/no ... usage.html

Thought this gave a pretty good explanation and may help others in the future.

Great thread there.

Though, I run synthetic myself and have seen no issues in the year and 20,000 miles that I've owned the car.

I've run synthetic for the past 115k miles and have had no issues.

From my understanding, the only reason Synthetic tends to be consumed (or leak) quicker is because the molecules are smaller in size, allowing them to seep though tight spaces that the larger conventional molecules wouldn't make it though...

I put 8 quarts in and run 6k-8k changes in our GXP and don't burn enough per change to justify a top-off (>1 qt.).

Mine doesn't get topped off either. Oil level does go down, but never worse than me adding half a quart in because I'm OCD. From the Cadillac Forums thread, it is important not to overfill when changing.

But, everyone's mileage will vary. Some may burn a quart per 1500 miles, some a quart per 3000, and so on.

So how often should these engines have their oil changed.

Loopy wrote:So how often should these engines have their oil changed.

As often as any other engine. 3-5k on conventional and 6-8k on synthetic. Of course, others may feel diferently.

The official answer from GM is to follow your Oil Life Monitor in your DIC.

I do 5000 miles on synthetic. I follow more extreme schedules than most because I do a lot of dense urban city driving with lots of stop and go. It usually works out to an indicated 50% on the Oil Life Monitor, but I ignore it.

If you followed your Oil Life Monitor you'd go 10k on a change, no matter the oil....

I go 7500 on our cars, based on 90% highway miles.

repinS wrote:Mine doesn't get topped off either. Oil level does go down, but never worse than me adding half a quart in because I'm OCD. From the Cadillac Forums thread, it is important not to overfill when changing.

But, everyone's mileage will vary. Some may burn a quart per 1500 miles, some a quart per 3000, and so on.

The ironic thing for me is how this all started for me because of my DIC and "low oil" warning. If that hadn't gone off, I would have no idea I'm even consuming oil as my N* sounds amazing, shows no leaks, and definitely isn't lacking in the performance department. It is nice hearing everyone's different experiences on the topic though, and it still amazing me how different each of these N*s can be. Even as much as I like using synthetic oil, I just figured I would see what kind of difference conventional oil would make since i had 2 mechanics recommend it for these engines. I'll try to remember and let you know what I find out.

I want to thank you guys again for the help. Chalk that one up for the "peace of mind" department as I really enjoy my GXP. Now for updating my rear 6x9s...

Every internal combustion engine on the planet consumes oil. Some more, some less. Even your lawn mower. If you haven't checked it in 6k, well yea, I would expect some form of consumption. EGR systems and PCV systems can sometime compound things. Go on to any of the LSx forums for the LSx motor, and look at how many people run catch-cans for the amount of oil those motors push back up and through the intake. The LS2 motor is really notorius.

Gagger14 wrote:Hey guys, i'm in a real predicament... Just found out my '04 GXP is losing oil through the exhaust and I'm not real sure what I wanna do. The seep is pretty slow (for now) as it took about 6k miles using mobil 1 high mileage synthetic oil for me to find out that it is indeed disappearing. I know its very expensive to fix oil leaks in these N*, money which I dont really have right now, and i've been told by a few knowledgeable ppl that I should trade it in before it gets bad. Problem is, I really like this car. Talked to my mechanic and he recommended trying AT-205 re-seal. Have any of you used this stuff before? Did it work? I can use any advice or knowledge on the topic as I would like to figure out my options.

Thanks for the help.

I have the same problem! I have a 2005 Bonneville GXP and it should not be using oil. I have no clue where the oil is going. Its not leaking any oil because I dont see abut I have to add neanything on my spotless garage floor. Any halp, its not leaking into the other fluids because it doesnt show up on any other levels. I am very confused, I also wiped my hand on the inside of the muffler I there is no signs of oil, it had a little carbon built up in the tail pipe but nothing alarming