Park Avenue using oil

[TopherS]

My 2001 Park Ave has over 125,000 miles on it now.

In the past 9 months to a year, I've noticed that as I take the car in for an oil change (every 3000 to 4000 miles), that I come in about 1 quart low. I don't remember it doing that before. I park in a garage and have not a single drop of oil on the garage floor. I haven't seen any smoke coming out the back, either.

I've also noticed that the engine is running a little rough lately, as well...but maybe it needs a tuneup.

I'm trying to decide whether this is a sign of impending doom for my car...or if it is something that is somewhat normal. I've read that some cars will use oil normally (I've recently read that about the Cadillac Northstar engines).

I've now switched to full synthetic oil and had the full cleanout service from Jiffy Lube (don't like them necessarily, but my mechanic has moved to a neighboring town...). Costs more at oil change time...but cheaper than car payments.

I've recently met another mechanic, but don't know much about him yet...and I want to have him look at the car...but is there some way to determine if I've got the beginnings of a major problem here?

Thanks in advance.

[gmtech1]

GM defines oil consumption for your vehicle to be "one quart or more in 2000 mi." If your driving 3-4000 miles and using only 1 quart, I would'nt worry too much about it. Your car has 125k on it, rings, valve seals and such no doubt have some wear on them, but unless your blowing blue smoke out the tail pipe, keep driving!

[Tech II]

IF THERE ARE NO EXTERNAL LEAKS, like at the lower intake or valve covers, or oil pan, or oil switch(this is usually a huge leaks) then watch for blue smoke on initial startup.....there have been some problems with valve stem seals....they have a metal ring around them that may break, and this causes the seapage down the valve stems...

[BNaylor]

Since you have the Series II 3800 engine check the PCV valve and o-ring located under the MAP sensor of the right hand side of the Plastic UIM Plenum. The oil consumption you have could be considered normal but doesn't hurt to check into it if the consumption was lower in the recent past. When did you switch to full synthetic oil? Before or after?

[TopherS]

Originally Posted by BNaylor

Since you have the Series II 3800 engine check the PCV valve and o-ring located under the MAP sensor of the right hand side of the Plastic UIM Plenum. The oil consumption you have could be considered normal but doesn't hurt to check into it if the consumption was lower in the recent past. When did you switch to full synthetic oil? Before or after?

About 5 years ago, I had the recommended repair that everyone with this engine needs. Is this what you're referring to? I believe it is.

I had switched to "high mileage" oil for the previous 2 oil changes. This last oil change is when I changed to the full synthetic.

GMTechI and TechII: I will go out and check for smoke. Here's hoping there isn't any...

[Jrs3800]

Funny this is mentioned... My 03 Bonneville with the series II( Naturally Aspirated Littler brother to the supercharged ).... Mine also uses 1 quart in 3000-4000 Miles... I have no leaks, engine is dry and the lower gaskets were replaced with GM aluminum gaskets... The PCV valve was also replaced to see if that changed anything... I still have the same issue... Mine runs a little off color, but not by much... I do believe this to be a flaw in the valve stem seals...

The series II in my 95 Bonneville uses 1/2 a quart in 3000... always has...

My 95 Van with a series I L27 never used a drop.... The current engine a series III 3800 under series II induction also doesn't burn a drop...


At the current I am not going to rip my 3800 in my 03 Bonneville apart to do the valve stem seals... I get no smoke on start up, not yet anyhow... I generally change the oil at 40% life, I'd say I add a quart at 3000 and change it at 5000 miles or so...

[TopherS]

UPDATE: Had the wife start up the car and I stood behind (good thing she isn't mad at me at the moment ). Anyhow...the only thing coming out the tailpipe is the little bit of condensation cloud...no smoke whatsoever.

jrs3800: Thanks for your input... How many miles do you have on your Bonnie's

[HotZ28]

Originally Posted by TopherS

UPDATE: Had the wife start up the car and I stood behind (good thing she isn't mad at me at the moment ). Anyhow...the only thing coming out the tailpipe is the little bit of condensation cloud...no smoke whatsoever.

On this particular engine (Series II) if parked on an incline, oil will accumulate in the lower valve cover (front or back depending on position of car) enough to flood the valve stem seals. The lower part of the heads do not have oil drain-back holes, hence the usual early signs of valve cover leaks. If the valve seals are hardened & leaking, (which I suspect is the case at 125K) a good test would be to park the car on an 20 deg incline (front end down) and let the engine idle for at least 10-min, then do a rapid full throttle (open/close) acceleration to check for smoke from the exhaust. More than likely the valve stem seals are beginning to loose oil control and will eventually clog the cat. It will only get worse the more miles you put on it. In addition, when the cat becomes restricted, do not install a new cat before installing valve seals, or you will soon destroy the new cat.

[Stealthee]

Switching to sythetic at higher mileage is not a good idea. I wouldn't be surprised if you saw your oil consumption go up now.

[Jrs3800]

Originally Posted by TopherS

UPDATE: Had the wife start up the car and I stood behind (good thing she isn't mad at me at the moment ). Anyhow...the only thing coming out the tailpipe is the little bit of condensation cloud...no smoke whatsoever.

jrs3800: Thanks for your input... How many miles do you have on your Bonnie's

the 95 Bonneville has 191,000 But the engine in it has 90,000 miles on it... Replaced it 4 years ago.. It burned a little oil then and still does now, no change at all.. Good thing in my eyes...

The original engine in the 95 Trans Sport was almost 180,000 when I pulled it for a light rod tap... Even then it still used no oil..

The engine I used in it was a Series III, it was said to have 40,000 miles on it, but when we opened it, it looked brand new.. I have tossed a cam in this motor and the goodies to go with it... This engine uses no oil, at least from what I can tell on the dip stick..

The 03 Bonneville has almost 83,000 Miles on it.. It burned a little oil early on, but as the miles increased so has the oil consumption.. Car still does 27-30 Mpg with me running 70-80 Mph car loaded down...

[Jrs3800]

Originally Posted by Stealthee

Switching to sythetic at higher mileage is not a good idea. I wouldn't be surprised if you saw your oil consumption go up now.

Curious as to what you are basing that on?

[Stealthee]

Proven facts. When using dino oil all a cars life seals "get used to" the dino oil. Switching to synthetic will allow MORE oil to get past the seals.

[Jrs3800]

While I would not switch an old chevy 350 from dino to synthetic due to the sealing technology used back in the day I would not hesitate to do this to a 3800 V6...


To the OP, while 1 quart of consumption in 3000-4000 Miles more than average for a 3800, I would live with this consumption and simply monitor it... Personally I favor engines that burn nothing, I have been spoiled buy most 3800's over the years not using any oil... This 03 Bonneville is the worst I have had in terms of oil burning... Again I have no smoke on start up, car has plenty of power for what it is... I will be taking this car back up home shortly... 1000 miles up and 1000 miles back... when I get there I will be 1/4 quart down... seems to burn a little less on the road... I figure its due to the engine turning 2000-2200 at 70-80 Mph as opposed to running everything up to 5000 Rpms...

Also curious if you have tried 5-30 high mileage?

[Stealthee]

Rubber seals are rubber seals. They react to oil the same whether its in an old school big block, or a 3800. Sealing technology on a 3800 is an oxymoron. All of the LIM problems, valve cover gasket problems and the like show just how poor they seal. Also the 3800 is a dinosaur. Its origins are from 1962.

[TopherS]

Originally Posted by Jrs3800

While I would not switch an old chevy 350 from dino to synthetic due to the sealing technology used back in the day I would not hesitate to do this to a 3800 V6...


To the OP, while 1 quart of consumption in 3000-4000 Miles more than average for a 3800, I would live with this consumption and simply monitor it... Personally I favor engines that burn nothing, I have been spoiled buy most 3800's over the years not using any oil... This 03 Bonneville is the worst I have had in terms of oil burning... Again I have no smoke on start up, car has plenty of power for what it is... I will be taking this car back up home shortly... 1000 miles up and 1000 miles back... when I get there I will be 1/4 quart down... seems to burn a little less on the road... I figure its due to the engine turning 2000-2200 at 70-80 Mph as opposed to running everything up to 5000 Rpms...

Also curious if you have tried 5-30 high mileage?

In the last 2 oil changes, I used the high mileage...not sure if 5-30 though...whatever the high mileage oil they used. My "oil level low" (or whatever it says) message would show up in the Driver Info Center and in looking at the sticker on the windshield...sure enough, I was about 3000-3500 miles since last oil change...I'd add oil to ensure I wouldn't run out and I'd get it to an oil change within a week or so.

By the way...the engine has been idling a little rough, as well. Do you think it's related...or just in need of a tuneup?