Hey y'all,

I have a 2008 Grand Prix GXP V8, and for the year I've owned her I've noticed on the freeway she tends to release large poofs of white/grey smoke out the exhaust, but only intermittently.

She guzzles oil, and the coolant is full, so I'm fairly confident she's just burning oil.

After doing some research, it looks like a common issue Grand Prix's of her year have is the displacement on demand system can cause her to guzzle up and burn oil.

Now, I've been leaving that system on because gas costs an absolute fortune, so every drop I can save is a worthwhile expense, but I'm also worried that this bad design for a DOD could be causing damage to the engine. Is that the case?

As in, I know its normal for engines to burn oil, and typically such wont cause any problems, but will allowing this much oil to get burned on the daily cause any problems in the long run? (She's my daily driver, so I'm on the freeway and seeing this every day). Aka, would it be worth the extra cost in gas to keep from causing more expensive problems later on? Or is there no real risk in letting her burn oil like this?

I should note I have a tuner, so it's not a big deal to disable the DOD.

Thanks

Edited September 26, 20232 yr by JSPitman

20 hours ago, JSPitman said:

Hey y'all,

I have a 2008 Grand Prix GXP V8, and for the year I've owned her I've noticed on the freeway she tends to release large poofs of white/grey smoke out the exhaust, but only intermittently.

She guzzles oil, and the coolant is full, so I'm fairly confident she's just burning oil.

After doing some research, it looks like a common issue Grand Prix's of her year have is the displacement on demand system can cause her to guzzle up and burn oil.

Now, I've been leaving that system on because gas costs an absolute fortune, so every drop I can save is a worthwhile expense, but I'm also worried that this bad design for a DOD could be causing damage to the engine. Is that the case?

As in, I know its normal for engines to burn oil, and typically such wont cause any problems, but will allowing this much oil to get burned on the daily cause any problems in the long run? (She's my daily driver, so I'm on the freeway and seeing this every day). Aka, would it be worth the extra cost in gas to keep from causing more expensive problems later on? Or is there no real risk in letting her burn oil like this?

I should note I have a tuner, so it's not a big deal to disable the DOD.

Thanks

There are several issues/problems with the LS4 V8. The first to be concerned with is the burning of oil will poison the cat! Causing it to fail, AKA quit working.
 

What you might consider doing. 1. Replace the PCV valve just as a precautionary measure. In the 5.3 these have been an issue. 2. Do a leak down compression check of all cylinders, not a momentary rotational one. A leak down test tells you a lot more about ring condition. 5.3 are known for having a problem with ring tension. 

Hey y'all, sorry for not responding to this right away, but I figured the more time to confirm the issue the better.

Turns out my theory that it was the Active Fuel Management (DOD) system causing the issue was accurate. I disabled it with a DiabloSport tuner, and she immediately stopped burning oil. Been almost 10k miles since then and no puffs of smoke and I haven't needed to top off the oil outside regular oil changes.

I figured it was worth making this note and resolution here for anyone in the future with a similar issue. Ancient forum threads with no resolution are one the banes of my existence.

On 9/27/2023 at 8:24 AM, Last Indian said:

There are several issues/problems with the LS4 V8. The first to be concerned with is the burning of oil will poison the cat! Causing it to fail, AKA quit working.
 

What you might consider doing. 1. Replace the PCV valve just as a precautionary measure. In the 5.3 these have been an issue. 2. Do a leak down compression check of all cylinders, not a momentary rotational one. A leak down test tells you a lot more about ring condition. 5.3 are known for having a problem with ring tension. 

In case she starts burning oil again, I'll keep these instructions in mind. Thanks for your suggestion on what might be going bad.

Edited December 12, 20241 yr by JSPitman