2006 750li oil recommendations, burning oil

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I'm not sure if this is oil quality/specification related but I thought that I would bounce it off you all. Have a 2006 750LI here that if left idling for 10+ minutes it will begin to smoke out of the exhaust (a fair amount of smoke). This smoke is blue and definitely oil related, smells like burning oil as well. It will not smoke on start up fyi. This vehicle was just at another facility for correction of this concern. They had replaced the PCV diaphragms and I believe that the PCV system is functioning correctly. Pulled all spark plugs and inspected, they all look perfect, brand new, so no direction here. Im wondering if too thin of an oil has been used in this engine or potentially the wrong oil in general. I would think that a 10w40 or 15w40 would be good in this engine, T6, AMSoil, Castrol, etc... Any thought? Thanks
 
Sounds like valve stem seals to me, but that usually also coincides with a puff of smoke at startup.

A cursory Googling shows that 750LIs of that vintage do often have this problem and that most enthusiast forums report replacing the valve stem seals cures the issue. However the repair does not look like it is for the faint of heart or novice mechanics.


A note from a BMW Technical Training manual you might find interesting:
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Note: If the exhaust system produces blue smoke, it is necessary to check whether the engine is also drawing oil into the combustion chamber through the crankcase breather, which suggest that there is a fault in the area of the crankcase breather. A clear sign of a problem is an oiled up clean-air pipe.
--

But if your PCV/CCV system is actually functioning correctly, I would think valve stem seals/guides are your next most likely culprit.
 
That is why I didn't think valve seals. There is a small amount of oil puddling in the PCV crossover tube but the valves were recently replaced. Also, when the engine was idling and smoking from the exhaust I disconnected the PCV valve and plugged, smoke continued from the exhaust even 10 minutes later. I would think that with in 10 minutes it would have burned up what left in the system and stopped smoking. Im thinking valve seals as well and yes it is a very intensive job, no doubt.
Originally Posted By: scurvy
Sounds like valve stem seals to me, but that usually also coincides with a puff of smoke at startup.

A cursory Googling shows that 750LIs of that vintage do often have this problem and that most enthusiast forums report replacing the valve stem seals cures the issue. However the repair does not look like it is for the faint of heart or novice mechanics.


A note from a BMW Technical Training manual you might find interesting:
--
Note: If the exhaust system produces blue smoke, it is necessary to check whether the engine is also drawing oil into the combustion chamber through the crankcase breather, which suggest that there is a fault in the area of the crankcase breather. A clear sign of a problem is an oiled up clean-air pipe.
--

But if your PCV/CCV system is actually functioning correctly, I would think valve stem seals/guides are your next most likely culprit.
 
Originally Posted By: scurvy
Sounds like valve stem seals to me, but that usually also coincides with a puff of smoke at startup.

A cursory Googling shows that 750LIs of that vintage do often have this problem and that most enthusiast forums report replacing the valve stem seals cures the issue. However the repair does not look like it is for the faint of heart or novice mechanics.


A note from a BMW Technical Training manual you might find interesting:
--
Note: If the exhaust system produces blue smoke, it is necessary to check whether the engine is also drawing oil into the combustion chamber through the crankcase breather, which suggest that there is a fault in the area of the crankcase breather. A clear sign of a problem is an oiled up clean-air pipe.
--

But if your PCV/CCV system is actually functioning correctly, I would think valve stem seals/guides are your next most likely culprit.


Yep, it is valve steam seal for sure!
On some cars it will not smoke at start, but after idling, good lord!
 
Best oil I have found for that issue is maxlife 10w-40, and maybe some 20W-50 mixed in there for the summer. Also, I have found that an additive called Schaeffers #132 is a high quality additive that slows oil consumption, smoking, and wear. I add it to oils in the summer for issues such as you describe, when it would be cost prohibitive to fix the real issue for my customers/friends. 132 is NOT just another STP clone. It just works, and so does maxlife.
 
We (at a small indy BMW shop) have had pretty good results with lubro moly's oil saver. We have a few customers with the same engine, N62 or N62TU, that need valve stem seals. A can of the oil saver stuff really does cut down oil smoke and consumption.
 
How much does it cost to replace the valve steam seals? I'm never a fan of using a band-aid to fix a problem like this.
 
Sounds like a great way to fry a few grand worth of catalytic converters.

Fix it properly, German cars don't do well with band aids.
 
Alldata says 32.6 hours to replace both heads, so that is close, plus some for the machine shop to actually replace the seals. The seals cost $75, plus head gaskets $150, intake $14, exhaust mani gaskets $40, valve cover gaskets $200, plus head bolts, not sure on cost. New oil and coolant. Plus other various gaskets and seals related to this huge job.

So with labor at $95 an hour, $3097 in labor
parts about 480, call it closer to 500, plus tax (in texas) that comes to $540
machine shop, $200 not sure about that, just a guess.

Total for valve stem seal replacement is about $3837.

So yeah, i'd try a $15 can of ester oil/ seal sweller. Heck, we have, it really does minimize the smoke and oil consumption.

Also, I hate to say it but these cars are not worth as much as some you think. Quick c-list search shows $14,000 to $18,000.
 
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From what you describe I think it's probably past the point where an additive or oil could help. But since it has to have oil in the sump it may as well be a high mileage type, Id try 10w40, M1 or similar for at least 2 OCI before making any judgment on it's effect.
 
I would first try an OCI of Mobil 1 HM 5W30 or even the 10W40 version. The other additives that have been mentioned, I have used and would not do much for your newer engine. How many miles on the car?
 
Originally Posted By: glxpassat
I can't understand why it wouldn't puff on start up if it's the valve seals...


Could be the oil separators causing pooling in the plenum maybe?
 
On some cars, the mechanic could just leave the engine heads in the car, but remove the cams and timing equipment. Next they would pressurize the cylinder to keep the valves in the closed position. At that point, they could remove the valve keepers and springs, r&r the stem seals, and the put the springs and keepers back.

Sometimes this is possible, but the OEM doesn't publish it in the manual, possibly to make the dealer as expensive as possible.

Do you have a specialty shop that does nothing but high end European cars? They may be able to do this procedure, I mentioned. Other times, their mechanics have discovered another trick to save you money.
 
Art,

it's not really feasible to do it like that on these cars. I've done that trick on many Japanese four cylinders, pop the valve cover off, hook air up, pop the spring retainers off, etc.. Easy on some cars.

These, the valve cover itself is half the job, not quick and easy. The rear cylinders would be VERY hard to get to the valves. Also, this car has adjustable valve lift so there is a 3rd "cam" on top of the intake cam. These cylinder heads are huge and cumbersome.
 
I would be tempted to change over to 10w40 Maxlife to see if there is an improvement.

This might help narrow things down.

Though would sticky oil control rings be another possibility?
 
big,

I'd bet money on valve stem seals, I've replaced them on a hand full of cars with this same engine.
 
^^^I would agree, as idling for a while and then belching smoke as you power up are very indicative of bad valve guide seals.

Stuck rings are still a possibility, but they don't normally exhibit the exact behavior described.

One word answer: Maxlife. It may take a while...
 
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