shaghil

I have 2005 BMW 545i. Great car! Drives wonderful. I have driven it for 16 years now. Looks like new. It has 170K miles on it. I like to keep it but it gives out blue smoke after idling for 3-4 minutes. Not much but enough to annoy me. If it idles for longer that 10 mins then it gives out more blue smoke when gas pedal is pressed. During regular normal running the runs fine without any smoke coming out. I have taken it to the BMW dealer. They recommended to replace the catalytic converter - a cost of $7000. I want to avoid the dealerships. They are just there to make money. Plus it is an old car so dealers are not the place to go. I took it another private mechanic whom I trust and works on German cars, and they said it is the valve stem cell seals. Everything is pointing to valve seals. Replacing the catalytic converter is not the answer as BMW dealer recommended based on the diagnostic code. But to replace valve seals is a big labor intensive job. The engine has to be opened and possibly taken out to make replacing the seals easier. The car is definitely burning oil but the car drives fine. My mechanic said just run it and add oil when low. Fixing the valve seals can be undertaken but there is no guarantee that other issues will not pop up when engine is opened, like piston rings. So, here I am still driving the car and waiting for the next Illinois emission test due next March 2021. It will not pass the emission test, That I know. My mechanic said to come to them before going the emission test facility so they can at least fix the service engine light on and replace oil. Then hopefully it will pass the test. Btw, I have replaced the PCVs twice but this did not help the smoking.

My questions to you:
1. Is this blue smoke bad for the engine if run for a long period?
2. Blue smoke does affect the catalytic converters with oil deposits. Is it worth replacing them?
3. Do you have any other recommendations for an old but looks like new beamer?

Thanks,
Shaghil
from Chicago

donpb

Sounds like valve stem seals, valve cover gasket or head gasket. Your indy mechanic should be able to tell you all that's causing it. Hopefully its just the valve stem seals.

dingolfing

I've had good success with using Mobil 1 full synthetic high-mileage oil. They come in either 5W-20 or 5W-30. I used the 5W-30. The high mileage oil has rubber seal conditioners that address the internal oil seals, including those valve stem seals.

After an oil change with this, it takes several months (up to half a year) for the seal conditioners to impregnate the rubber seals. I could idle for long periods without any smoke.

I suggest only using the Mobil 1 high mileage oil. On my next oil change, I could only find Castrol full synthetic high mileage and used that, and the oil burning came back.

Obviously, this is just a band aid and the proper fix is to replace the valve stem seals. But using this oil is much cheaper than performing the actual surgery for a car this old.