I have a 2005 g35 coupe. The car has 80k on it. Started burning oil a couple of years ago. It would burn 1 qt every 1500 miles.
One year ago, I would put one qt every 750 miles or so. 6 months ago, 1 qt every 300 miles.
Now its so bad that it consumes 1 qt every 75-100 miles! It is really insane.
On startup the car lets out huge puffs off smoke and even drops of oil come out of the tailpipes upon punching the gas. Spark plugs have never been changed yet. Car rides good otherwise. Is the engine shot? Piston rings?
Thanks

 

Well it does not sound good, it looks from your description like the engine has deteriorated a bit early, I would not expect that from an engine with 80K. Almost all of us experience oil loss due to wear and or leaks.

You say piston rings, yes most likely. Worn valve guide seals are also a possibility. I would venture to say that you are probably leaking oil from your valve covers also adding to your total loss. Have you checked for external leaks? What weight oil are you currently using? Consider using the heaviest weight permitted by the engine specifications, it might help a little. An oil catch can might also help some. I would recommend that you do a compression check to see if it is one particular cylinder blowing oil by or if all are at fault. Definitely some basic trouble shooting is needed.

Good luck,

 

If it's a re-up then you probably have the dreaded oil consumption problem..

 

I have a 04 coupe, and I have the exact same problems as you do....I have 110k Kilometers so 68k miles...I might actually burn a bit more than you. Same smoke at start and oil out of pipes. But the car runs great and I don't really notice power loss. Probably this summer I will find a engine and get it replaced

 

Are you the first and only owner of the car? 68K miles on a non-revUP motor is really low to be burning that kind of oil. What kind of oil are you using?

 

I am the second owner of the car, I bought it last winter and did an oil change 2 days after, I used 5w30 Amsoil Synthetic. A week later I checked the oil and it was at L... so I just topped it off, but the synthetic burned very fast. So summer time I switched to 10w30 Conventional, and I only have to top it off every 2-3 days, depending on my driving. So I will probably find a engine this summer

 

Ah crap. Sounds like the original owner may have beaten that thing like it owed him money. Did you get a good deal on it at least?

 

I wonder if you have blowby at the cylinder level. If you get someone who has a inspection cam you can check if the cross hatch surface of the cylinder wall had failed. If the hatch is worn badly, your engine walls will retain oil during combustion, burning hefty amounts of oil...

This is something a little more in depth, but if you are looking for an answer you have to check the touch stuff.

 

Yeah I got a good deal lol, the car is super clean interior/exterior.

 

Keep an eye out for signs of problems on the other drivetrain components such as tranny, drivetrain joints, differential and CV's. It's possible that the previous owner just did something dumb that caused the motor exclusively to take some serious abuse, such as not changing the oil regularly or running it with almost no oil, etc. But if the reason for the short life of the motor was abuse, then I would expect other components to also be prone to premature failure.

 

Yeah will do, but everything else does seem alright. Only thing that worries me is that the clutch was replaced at 100k km's, I heard OEM clutches go till 100k+ miles.

 

That all depends on the person's driving habits. Could be that they did a lot of stop and go driving in heavy traffic.... or maybe they just didn't use proper manual transmission driving habits such as not riding the clutch, etc. Original clutches on just about any vehicle can last from 15K to infinite miles depending on how you use them. Mileage basically is not a good measuring stick of how badly worn a clutch is. If a guy drives his car 130 miles each way every day to work and it's all highway driving with almost no stops, then his clutch could last 400K+ miles and still be A-OK while another guy might do nonstop heavy traffic every day with constant starts and stops on big hills and his clutch in the same vehicle could be dead after 15K miles.

 

When was the last time any of you guys with the oil consumption problem replaced the PCV valve? On the BMW forum which I am also a member, the CCV system can clog to the point that it create a high enough vacuum to suck oil from the oil pan into the intake manifold and hydro lock the engine.

 

PCV Valve was the first thing I tried lol, it didn't change anything.