Definitely using/losing more oil

[Benzadmiral]

The 3.8L in the Buick is definitely using, or losing, more oil. After I did the first change to PP, its "Engine Oil Level Low" message came on at ~2600 miles, and I had to add a quart. That continued with the following PP changes. When I switched to Castrol GTX for one change, it took about 2800 miles to get to the low point, and about the same when I used NAPA synthetic. (All 5W-30s.)

Now I've got Castrol Edge 5W-30 in there -- changed at 73,350, car is now at 75,900 -- and I've had to add two quarts in 2500 miles!

I'll put some cardboard under the car when I park it on Friday night, to see if there's any dripping. And I'll check to see if there's any blue smoke coming from the tailpipe (I don't see any in my rear view when I drive, nor when I have the car idling). But could it be the thinness of the Castrol Edge? Do you think switching to a thicker 5W or 10W-30 will help, or should I consider an HM oil?

 

[Drew99GT]

Our 3.8L has had 2 leak points - the oil pressure sender (right above the oil filter - if that area is covered with oil, it's likely the sender), and the rear crank seal. I'd check those out. FWIW, it never dripped onto the ground from those 2 points, but the underside of the car (Olds 88) had a lot of oil everywhere.

 

[Trav]

How many miles on the engine? At 1 qt every 1K chances are the cat will burn it off before you see any smoke in the rear view mirror. Look for leaks,it doesn't take a huge leak to use this amount of oil in that mileage,it may only be leaking with the engine running and getting blown around under the car while driving.

If no leaks are found try running Kreen,BG109 or a full OCI with MMO before going to heavier or HM oils.
Did this just start happening?

 

[addyguy]

I'd give a HM oil a try, just to see if it helps.

Can't hurt.

 

[Benzadmiral]

Originally Posted By: Trav
How many miles on the engine? At 1 qt every 1K chances are the cat will burn it off before you see any smoke in the rear view mirror. Look for leaks,it doesn't take a huge leak to use this amount of oil in that mileage,it may only be leaking with the engine running and getting blown around under the car while driving.

If no leaks are found try running Kreen,BG109 or a full OCI with MMO before going to heavier or HM oils.
Did this just start happening?

The engine has 75,900 miles on it. No, as I said, I'd been losing some oil almost since I bought the car in late '07, but since it was about 1 quart in 5K miles I didn't worry much. Now it looks like four (!!) times that. And it started soon after I went to Castrol Edge -- so I have to wonder (I can't conclude it yet) if there's a connection.

 

[Benzadmiral]

Originally Posted By: Drew99GT
Our 3.8L has had 2 leak points - the oil pressure sender (right above the oil filter - if that area is covered with oil, it's likely the sender), and the rear crank seal. I'd check those out. FWIW, it never dripped onto the ground from those 2 points, but the underside of the car (Olds 88) had a lot of oil everywhere.

Hmmm. My regular mechanic just changed the oil pressure sender earlier this year -- late March, about a week or so before the Castrol Edge went in. I didn't notice any serious oil under the car when I was attempting to change it myself at that time, but I could have overlooked it.

 

[daves87rs]

Time for 10w30?

 

[Trav]

I doubt the edge has anything to do with this issue.Look at the oil pressure sender as Drew pointed out and also take a close look at the valve cover gaskets and grommets,weeping grommets and gaskets can weep a qt every 1k and the only sign of it would be a slight oil smell occasionally as it goes up in smoke.
Have you changed the PCV valve located in the front of the upper plenum?

79K is nothing on this engine,the 3800 is very durable and is a 100k away from being high mileage,try to find and fix the issue instead of masking it with heavy oils.

If you find no leaks it just may have sticking rings depending on if it has been babied,then try Kreen or MMO for a few thousand or BG 109 before an oil change to free them up.

Edit Just for laughs check the oil filter,we had a Camry in that was using oil with no obvious signs,the filter was weeping when the engine was running,it was ever so slightly loose

 

[Benzadmiral]

Originally Posted By: daves87rs
Time for 10w30?

I'm beginning to think so. The quart I popped in yesterday was Mobil Clean 5000 10W-30 -- and it's got a cSt of 10.6 at 100 C., as compared to Castrol Edge's 9.8. If I have to add another quart (!) before I change oil in October/November, it'll be 10W-30 as well.

 

[Benzadmiral]

Originally Posted By: Trav
I doubt the edge has anything to do with this issue.Look at the oil pressure sender as Drew pointed out and also take a close look at the valve cover gaskets and grommets,weeping grommets and gaskets can weep a qt every 1k and the only sign of it would be a slight oil smell occasionally as it goes up in smoke.
Have you changed the PCV valve located in the front of the upper plenum?

79K is nothing on this engine,the 3800 is very durable and is a 100k away from being high mileage,try to find and fix the issue instead of masking it with heavy oils.

If you find no leaks it just may have sticking rings depending on if it has been babied,then try Kreen or MMO for a few thousand or BG 109 before an oil change to free them up.


Yep, I changed the PCV valve twice myself -- once when I got the car, and once last summer. Both were OEM parts, too.

 

[Trav]

I edited my last post to include.
Edit Just for laughs check the oil filter,we had a Camry in that was using oil with no obvious signs,the filter was weeping when the engine was running,it was ever so slightly loose

 

[Benzadmiral]

Originally Posted By: Trav
I edited my last post to include.
Edit Just for laughs check the oil filter,we had a Camry in that was using oil with no obvious signs,the filter was weeping when the engine was running,it was ever so slightly loose

True, this increase began right after my last oil change. I'll put it up on the curb this weekend and have a look.

 

[Johnny]

Didn't the 03 Buick with the 3.8 recommend 10W-30? I had an 03 Pontiac Gran Prix with the 3.8 as a company car and it recommended 10W-30. When I retired in 2005 that car had way over 100K on it and it did not consume a drop of oil.

 

[Benzadmiral]

Originally Posted By: Johnny
Didn't the 03 Buick with the 3.8 recommend 10W-30? I had an 03 Pontiac Gran Prix with the 3.8 as a company car and it recommended 10W-30. When I retired in 2005 that car had way over 100K on it and it did not consume a drop of oil.

True, the manual does recommend it for moderate temps. In there it suggests that if outside temps are below some point, possibly freezing, then it's okay to use 5W-30, and if it's below zero F., synthetic 0W-30 is fine. (I'm guessing at the temp points, but they sound familiar.)

On the other hand, the oil filler cap says 5W-30. Since that could have been swapped in from a later car, that's not definitive. . . .

 

[addyguy]

Where you live, with a 3.8 using oil, a 10W-40 wouldn't be out of the question.

 

[snoops454]

Originally Posted By: Johnny
Didn't the 03 Buick with the 3.8 recommend 10W-30? I had an 03 Pontiac Gran Prix with the 3.8 as a company car and it recommended 10W-30. When I retired in 2005 that car had way over 100K on it and it did not consume a drop of oil.


My parents had a LeSabre they just got rid of and it spec'd 10-30 at almost 200k that car didn't use a drop of oil, was run on 10-30 conventional what was on sale. Mostly Trop Arctic, Havoline, Valvoline, Ect... Car ran perfect, I did all the maintenance for them, dad got bored and wanted a different car.

That Edge is on the thin side for a 30 wt oil...

 

[Trav]

-2005 10w30 was specified 2005 and later 5w-30 year round all climates.
The 2004 was a Gen III engine and spec is 10w-30 while the 2005 is 5w-30 and is the same exact engine.

The Gen III engine is the same engine as the Gen II with different rod materials,aluminum intake,different size valves etc but the clearances which would be the primary reason for requiring a different weight oil remain the same.
IMO technically there should be no reason not to run 5w-30.

 

[mechtech2]

I'd switch to a HM dino. Cheaper, and should help.
The synthetics have done nothing for you.

 

[Benzadmiral]

Update,

I wasn't able to score any cardboard this time, so I parked the car last night and inspected the ground before I left. When I came out this morning, there didn't seem to be any fresh oil spots. Just now I put the Buick up on the curb and wormed underneath. The oil filter and drain plug are not loose; there are no leaks; the undercarriage is dirty, of course, but not oily.

On top, the forward valve cover and the pipes below it are dry. The rear cover is hard to see, though there may be a little sludge around one of the bolts. It doesn't look or smell like it has an oil leak serious enough to lose a quart in 1250 miles.

I'll have my regular guy check his work on the oil pressure sender (though I probed all around the filter with my gloved hand, and there was no fresh oil). In the meantime, should I just keep feeding it dino until I change this fall? Maybe run a pint of MMO in it during the last 500 miles?

Yes, mechtech2, the synthetics have been an interesting experiment, allowing me to extend my drain intervals without worrying, and I was able to do it, thanks to sales, at the cost of dino. But I saw less consumption with the Chevron and Castrol GTX, with the Edge being the worst.

 

[RacerE7773]

GM W bodies are notorious for Lower Intake Manifold gaskets being bad (no wonder GM almost went under. They still won't fix these but they will worry about profits rather than getting repeat customers. I'm done with GM) on the 3.4 (my '03 Impala) and the 3.8.

We had a oil light go on once, but we had not checked the oil in 2 1/2 months, so it leaked 2 qts from that area. It doesn't do it when it's parked; mainly when the system is under pressure it loses the oil. I'll keep up on the changes and when I can get enough money saved will get the gasket replaced. But I told my wife if she smells smoke and then see fire, let him burn. Makes you wonder where these "design engineers" get their degrees. Maybe cracker jack since they only have paper type of "prizes" now.