3800 Series III V6 oil consumption

[GM-midsize-guy]

Hi folks:

 

I'm going to put this here since it's more general in its applicability than the powertrain sub-forum.

 

After owning an early '90s 3800 V6 that used only ~ 1/4 of a quart of oil in between 3,000 mile oil changes (for almost up to 275,000 miles), I am stunned, disappointed, and even mad that my 2008 LaCrosse with a Series III 3800 V6 is using way more oil than my first and only other W-body.

 

I am aware there is a technical bulletin out there and I've read it. It has to do with exhaust valve seals. I can't believe that this heirloom engine would be released with this problem, and for about 4 years - 2005 to 2008! I've also read that GM stated that up to 1 quart of oil every 2,000 miles is normal. Not to me! Our family has never had a GM car we purchased new need much, if any, oil in between oil changes.

 

The consumption is about this: 4 out of 5 dots down on the operating range dipstick in 2,100 miles. That means one quart every 2,625 miles, doing the math. The car has slightly more > 30,000+ miles. No other problems have shown up with the car in 6 years and highway mileage is at about 30 or 31 mpg, so I'm thinking the engine is tight and tuned.

 

Some questions:

1. There are no leaks. Is this probably a "slight" problem with the valve seals or could it be tolerances in the engine?

2. Can it conceivably just consume that amount of oil and stay at that range of consumption for a long time? I could almost live with that, though I hate checking oil so often on a car that's been treated with kid gloves.

3. I've read stories (other forums, etc.) that some people have had this fixed and it worked, and that others have had this fixed and it did NOT work. I've seen the illustrations in the technical bulletin. How hard can it be the replace the valve seals? I'm thinking it could be done with the valve covers off ... or do the cylinder heads need to come off as well?

4. If you or anyone you know have had this problem with this engine, what have you or they done and did it work?

 

Are you folks with late model Series III 3800 V6 W-bodies liking your cars ... or not? Thanks!

[Buick666]

My 3800 Series II doesint burn a single drop of oil at 260 000km's... so yeah you're Series III does have a problem.

[l67ss]

Yes you can change valve seals w/o pulling heads, you just need compressed air and a fitting to thread into the plug holes

[Euro]

I had a Series III long block in my Grand Prix, and I never used a drop of oil that I can remember. But my dad's old 04 Impala LS with the Series II used a decent amount of oil through the life of an oil change. We thought it was strange as well, because his other 3800 he owned did not, nor did either Series II/III that was in my GP. But every mechanic(dealer and others) told him that GM had put out something saying it was "normal" for a 3800 to use a certain amount.

[White93z34]

the L67 in my car has 150,000 on it now with original valve seals. When I put the engine in the car I replaced every gasket short of timing cover and head gaskets.

 

Perhaps you have a slight intake gasket leak that is allowing oil to be consumed either externally or internally? I don't know if they were still using plastic lower intake gaskets by that time.

 

I use just under 1 quart in 5,000 miles generally which seems pretty good to me. What intervals do you run oil changes to?

 

Even my broke-ass 190k L36 that sounded like a rock tumbler for 70,000 miles didn't use all that much oil. IIRC it was good for a quart by 3000 miles.

[GM-midsize-guy]

the L67 in my car has 150,000 on it now with original valve seals. When I put the engine in the car I replaced every gasket short of timing cover and head gaskets.

 

Perhaps you have a slight intake gasket leak that is allowing oil to be consumed either externally or internally? I don't know if they were still using plastic lower intake gaskets by that time.

 

I use just under 1 quart in 5,000 miles generally which seems pretty good to me. What intervals do you run oil changes to?

 

Even my broke-ass 190k L36 that sounded like a rock tumbler for 70,000 miles didn't use all that much oil. IIRC it was good for a quart by 3000 miles.

 

Thanks for the response. Series III definitely did away with the plastic intake components; that was Series II, and it was hit and miss as to which batch got them. The intake manifold construction is aluminum, and they strengthened the connecting rods and also the oil pan construction.

 

I changed my oil at break in for the first time at 1,500 miles. Since then, I have changed the oil every 2,500 miles, so it's 4 times every 10,000 miles. Easy for me to track that way instead of every 3,000. Also, it's a low mileage car.

 

Another quirk: Since the last oil change, the amount used, per OP, has been bad. On the oil change before that, it was a super long interstate trip and it only used half a quart, which I STILL thought was ridiculous for a car that had 27,000 miles on it.

 

My last 3800, at 275K, wasn't burning any oil. That car was so hassle free. This car rides smoother and handles more "Lexus like," I guess, but I thought that a Series III, bought in its 4th year since its release, would never act up like this.

[GM-midsize-guy]

Yes you can change valve seals w/o pulling heads, you just need compressed air and a fitting to thread into the plug holes

 

Thanks. If it comes to that, I won't be doing it myself. But it tells me what I'd be discussing. The diagram in the technical bulletin shows just the valve covers off.