engine blue smoke?

[fly]

I have a 1993 525i - 5spd, w/ 85k miles on it. It runs good most of time, however, sometimes at startup it will run rough and belch blue smoke(oil smoke). It will eventually clear up and run ok.

I have pulled all 6 plugs and they seem to be a little dark, but none are darker than others.

I have been running shell rotella 15w-40 non-synthetic oil in it, it does seem to use a little oil too. My question is where do I begin diagnosing the engine? Is this wrong oil for this car? thanks all Brian.

 

[Big Daddy]

I think you should be using a 0w-40, however how much oil is "a little"? Is it a quart between changes or more? When was the last time you had a full tune up and/or changed the plugs? Do you know what plugs are in it?

 

[E30m42cab]

My guess would be your valve seal rings. When the car is driving, the oil will seep through these seals, and burn off fairly unnoticed as far as smoke goes, but you will lose oil for sure, along with the oil that will be burt off from regular driving through the piston rings. However, when the car sits and cools off, the valve seals will allow the oil to seep through into the combustion chamber from the cylinder head, and will sit there, and build up until the next start. When you start it up, it'll burn off of course, but your plugs will eventually get caked up and need cleaning/replacing frequently. The car will definately start poorly when this happens, and run smoother once the oil has been burnt off. The long term effect is not pretty... your pistons will become caked with the carbon, as will your valves. This is my educated guess, as my experience with one of my old M20 engines would teach me... granted, this is a M50 we're talking about, but the same thing can happen just as easily.

(repair kit BMW part #11349064457) you'll need two kits, one for each cam... I don't have a clue what the labour cost involved would be. I don't think your oil is a factor at all. ( I could suggest a different oil, but we'd all be here forever arguing what you should use.)