Buick 3.8 uses 2 quarts of oil between changes

[Gibby]

Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

[Ed Pawlowski]

On Tue, 30 Jul 2013 00:18:00 +0000, Gibby

Post by Gibby
Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

I'd guess that it is burning it. While it may seem high, a quart
every 1000 miles is still the accepted mark for "normal" consumption.
Given how much it is using, I'd save money and use regular, not high
priced synthetic. Sure, it is better, but you can't prove it by your
engine.

FWIW, my last GM 3.8 had 125,000 miles and the oil was changed every
7500 miles. Only once did I have to add oil between changes.

[Paul in Houston TX]

Post by Gibby
Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

You won't see any smoke if the cat is working right.
Its unlikely the metal is absorbing all the oil.

My 3.3 (same basic engine as the 3.8) went 250k.
O&F every ~7500. Rarely had to add oil.
The engine was still great but the rest of the car wore out.

[Ashton Crusher]

On Mon, 29 Jul 2013 21:37:17 -0500, Paul in Houston TX

Post by Paul in Houston TX

Post by Gibby
Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

You won't see any smoke if the cat is working right.

You won't see any smoke even without a converter until an engine is
burning oil faster then a quart every 500 miles based on my experience
with a GM 350 that burned a quart every 500 miles since the time I
bought it at 24K miles till I sold it at 120K miles. The whole time I
owned it I never saw even a puff of smoke and it had zero leaks.

Post by Paul in Houston TX
Its unlikely the metal is absorbing all the oil.
My 3.3 (same basic engine as the 3.8) went 250k.
O&F every ~7500. Rarely had to add oil.
The engine was still great but the rest of the car wore out.

[Vic Smith]

Post by Ashton Crusher
On Mon, 29 Jul 2013 21:37:17 -0500, Paul in Houston TX

Post by Paul in Houston TX

Post by Gibby
Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

You won't see any smoke if the cat is working right.

You won't see any smoke even without a converter until an engine is
burning oil faster then a quart every 500 miles based on my experience
with a GM 350 that burned a quart every 500 miles since the time I
bought it at 24K miles till I sold it at 120K miles. The whole time I
owned it I never saw even a puff of smoke and it had zero leaks.

At first I was thinking "2 quarts between oil changes, that's pretty
bad."
Then I see it's 6000 miles, and think some more.
I used to change oil at 2500, and most my cars burned 1/2 to a full
quart, especially if I was running a lot of high speed.
My 2 350's weren't any different.
A quart every 500 would bug me, and I had a Ford PU with a 352 that
did that, except more like 300 miles. Bugged me bad.
Especially since I personally rebuilt that engine except for having a
speed shop do the micrometer work and give me bearing and ring sizes
to use, and do the block bath. And I had a head shop do the heads.
They fucked up on the valve seals, and it sucked oil at high vacuum.
Did a 2000 mile road trip and it used less than 1/2 quart.
But around the city in stop-and-go, it just sucked in the oil.
As you say though, it didn't smoke. No cat.
So 2 quarts every 6000 isn't anything I'd worry about.
Not much anyway, especially if I was running it at +70 mph a lot.

[Ashton Crusher]

On Sat, 03 Aug 2013 11:17:44 -0500, Vic Smith

Post by Vic Smith

Post by Ashton Crusher
On Mon, 29 Jul 2013 21:37:17 -0500, Paul in Houston TX

Post by Paul in Houston TX

Post by Gibby
Buick 3.8 30000 miles uses 2 quarts between oil changes at 6000 miles, using
5w30w full synthetic. This is the 2nd 3.8 that has done this. No smoke, no
leaks what about metal absorption? Any other thoughts?

You won't see any smoke if the cat is working right.

You won't see any smoke even without a converter until an engine is
burning oil faster then a quart every 500 miles based on my experience
with a GM 350 that burned a quart every 500 miles since the time I
bought it at 24K miles till I sold it at 120K miles. The whole time I
owned it I never saw even a puff of smoke and it had zero leaks.

At first I was thinking "2 quarts between oil changes, that's pretty
bad."
Then I see it's 6000 miles, and think some more.
I used to change oil at 2500, and most my cars burned 1/2 to a full
quart, especially if I was running a lot of high speed.
My 2 350's weren't any different.
A quart every 500 would bug me, and I had a Ford PU with a 352 that
did that, except more like 300 miles. Bugged me bad.
Especially since I personally rebuilt that engine except for having a
speed shop do the micrometer work and give me bearing and ring sizes
to use, and do the block bath. And I had a head shop do the heads.
They fucked up on the valve seals, and it sucked oil at high vacuum.
Did a 2000 mile road trip and it used less than 1/2 quart.
But around the city in stop-and-go, it just sucked in the oil.
As you say though, it didn't smoke. No cat.
So 2 quarts every 6000 isn't anything I'd worry about.
Not much anyway, especially if I was running it at +70 mph a lot.

And the typical person who never checks there oil and changes it every
3000 to 6000 miles would never even know it's using any oil since even
at 2 quarts low the oil light would never come on. In my Blazer it
would get as low as 2 quarts before the gauge would start to show low.
Most of the time I noticed it on a longer trip at high speed, it would
start to have a lot of oil "up top" in circulation and then the
lifters would start to starve for oil and get noisy. So I'd slow down
for the next 50 miles till I hit a gas station and could put more oil
in.

[Geoff Welsh]

<snip> In my Blazer it
would get as low as 2 quarts before the gauge would start to show low.
</snip>

Of course, all the "extra" oil in the pan is just for going up very
steep hills and turning sharply.....and to make it seem clean longer.

On that radio show "Car Talk" a few years back, one of the guys had some
old beater that required the same amount of oil added, per miles, as a
car that burned no oil that had normal oil changes....so he never had to
change the oil. Perfect! (Unless you care about the planet, or need to
pass emissions. Nothing worse than a VW bus with a "save the planet"
bumper sticker, billowing black smoke as it drives down the road)

GW