I have a 05 Cavalier that is burning oil quite rapidly. The only time I see blue smoke out my exhaust is when I floor it from a dead stop as the car shifts into 2nd and 3rd gear (specifically when the RPMs drop, the smoke comes out). So far I have replaced the valve cover and intake manifold per a GM service bulletin http://www.chevelles.com/forums/showpost.php?s=c59ce774a3bf2c76f6115f82b90879b8&p=1769322&postcount=2 , I have replaced the head with a re-manufactured one, timing chain, I've cleaned and resealed the oil pan. It doesn't leak any oil, I park in the same spot every day. A compression test yielded 175-180 lb/in squared on all 4 cylinders. The spark plugs are NOT fouled, just normal spark plug wear. I would really like to figure out what is going on with my engine.

Can someone give me more diagnosing tools, or offer a possible explanation?

I recently experienced something similar but had NO oil burn, just missing oil. About a gallon in 5000km (synthetic) on a 00 2.4. A a friend informed me that some of the engines develope an problem apparently caused by oil switching. Mineral to Synth to Miner (your fine here) but back to Synth causes the problem. I myself have only ran synthetic in mine. Although I am 3rd owner at least. But the problem is something (forgive me I was half listening) to do with the valve seals and it blows the oil back out the intake valves.

I changed my oil because it was due, and I havent lost a drop since so I I think my problem was too many cold starts and runs over the cold winter. I recently installed a cold air and when I pulled the airbox off the plenum of the TB was black as can be and a light film of oil inside of airbox. I ran the car to temp, bought some kleen flow TBI cleaner. Pull the air intake system off, do this where its not going to be dusty as you now have no filter system.

Car running spray the cleaner into the plenum. Work the throttle plate by hand, but use a light touch, open only enough to keep from stalling, let it trip and stumble letting in enough air to prevent a stall. The cleaner will clean up the TB nicely, usually only need to run about a half can (1 minute) when your done spray heavily and let go of the throttle and let the engine stall out while spraying. Shut the key off and let it sit for a bit. 10 mins or so. Start it up and take it for a quick drive, but get it to pull hard (auto shift it manually) this will help clear out deposits on the Valves.

See if this helps, an alternative to this and works great is send it to a shop and have them do a motorvac on it. (same idea as what was just done but a machine does it) And a higher concentrated cleaner is used. Works wonders on the fuel system, helps clean out injectors and the fuel delivery system.


Question does it burn once up to temp?? They are prone to piston slap cold and that will cause some burn (which was my issue over the winter)

I replaced the head, so I don't think it's the valves.. I am also experiencing oil disappearing, at a large rate. I am constantly dumping 1-2 quarts into it every week - 1.5 weeks. I drive 50 miles a day on the interstate.

The engine will put oil out the exhaust whether the engine is cold or up to temperature. A friend of mine said it could be the piston rings (I really should have changed those anyway when I head the head off .. I'm far from a mechanic, but is there a way I'm getting blow by without my spark plugs fouling?

Try isolating the PCV valve from the rest of the engine.
You can do this buy buying a cheap oil/air separator on ebay and get a small breather filter. Install it, then drive the car for a day or whatever it takes for you to get a significant amount of oil blow by. Then empty the oil/air seperator and if a bunch of oil comes out then your problem is your pcv valve (which is not serviceable btw). If this is the case, all the oil coming out of the pcv valve is getting sucked back into your intake, causing it to get burned, hence the blue smoke.
However, it could also be being caused by excessive crank case pressure. Meaning the PCV valve could be doing it''s job as it should be. If you have excessive crank case pressure, check for blocked passages or vacuum lines. I'm not sure what else causes excessive crank case pressure, but I'm sure someone else could chime in on that.

Now as for me, I was having the same problem you are describing, but not to the degree you have. I was losing a quart every 1000 miles or so, sometimes 2000 miles. Now GM says that's fine for these cars, but I didn't like it. So what I did was isolated the pcv from the intake, and bingo, solved my issue. I'm not sure what was going on, but I did a ver simple test of making my ONLY change was adding a breather filter to the pcv. My oil consumption dropped dramatically, and now I use a quart every 3000 miles, on the dot. Never changes now. Works like clockwork. Honestly, I believe the dramatic drop has something related to the negative pressure in the intake manifold basically "pulling" the oil through the pcv valve, causing it to use more oil, than without that negative pressure, and just atmopheric pressure on the pcv.

Hope this helps ya out.

Another note to add, I took a piece of printer paper to my exhaust today and found I have a ton of black smoke and crud leaving my exhaust, meaning it's running too rich from what I've read. It doesn't have a carburetor, so how do i lean out the fuel?

You don't. The computer does. If it's running rich but running properly, then you need a scan tool, like a tech II to find out what the fuel trim data is and why. If you don't do that, then your just gonna throw parts at it.

Took the pistons out today, had some shocking surprises.


The connecting rod bearing was scored and out of round, like it had been run dry on oil. Somehow it doesn't appear to have affected the crank bearing journal?

boy packed up oil control rings and that rod bearing is wow what oil do you use?


see ya!

The previous owner never changed the oil from the looks of it. I use valvoline 5w-30.

I replaced the piston rings, connecting rod bearings, and cleaned out the fuel injectors with some pressurized carb cleaner, a syringe, and a 12v momentary switch to pulse the fluid through. I replaced the o-rings also. I put everything back together but now the car won't start. The starter spins and spins but nothing happens. The fuel rail has pressure, everything is plugged in, the fuel pump turns on when the key is turned, the sparks are occurring, but it won't start.. help!?

Le sigh, if you ever have someone assist you with timing your engine, make sure they read the manual and don't have TWO "INT" markers at 10 and 2...

Corrected the timing and it fired right up. After replacing the piston rings I have no smoke out my exhaust!