2001 BMW 318 White Smoke from engine at idle for 2001 BMW 3

A question about my bimmer. I own a 2001 BMW 318 CI, 83k miles on it. its the 1995 cc 4 cylinder engine. I bought it a few months back at 78k miles and I am loving it, no problems with it.

Anyway yesterday I changed out the spark plugs and put in the OEM NKG sparks. Also opened up the oil filter to check its condition. Previous owner told me he had done an oil service on it before i bought it and by the condition of the filter that seems correct. So after doing all of that I packed everything up, putting the engine cover on, holder for microfilter etc. which I had removed to change the spark plugs.

Now I ran the engine from cold to check if everything I did worked. It started without any problem. Since it was a cold start the engine obviously started at a higher rev (around 1100 rpm) and after a minute it dropped to around 700rpm as the engine warmed up. So far so good.

However just at the EXACT time when the revs at idle go from high to low, white smoke started coming out from the area I point at in the attached video at 1.50 minutes. However I have the camera trained at the point throughout the video.

(VIDEO - http://www.youtube.com/watch?v=FBSV9NMdI3c&feature=player_embedded

Is there anything I could have done (sparks, oil filter, moving pipes around to gain access to sparks) which has caused this smoke? Its not a lot and I can not quite figure out what the smell is, not rubber anyway.

I drove the car after and it runs fine, in fact pick up has improved thanks to the new sparks. I checked the engine after and no smoke. The smoke only comes when I start the car from cold and when the revs drop as it warms up, usually within 1 minute.

I assumed I spilt something however the smoke is still there after a few days, you would think it will have burned off, UNLESS there is a constant source supplying it. I did a bit more looking around and I think there is a small oil leak from the engine block.

my theory is that the oil is dripping onto the front end of the exhaust pipe and burning off. since it happens only at idle i am assuming only the exhaust would be hot enough at this point to burn off the oil. however the smoke dissapears once the car has been driven, so that is a mystery. after driving and stopping the car and idling it, there is no smoke. smoke only comes when car is started from cold, about 1 minute from starting when the engine warms up enough for revs to drop from initial 1100rpm to 700rpm.

as for the location of the smoke, it is coming from the back end of the engine block. the same block which houses the spark plugs, but from the back. or in other words the side facing you when you sit in the drivers seat. i touched the back of it and found some fresh-ish oil, which re affirms my oil leak theory.

However i have periodically checked the oil levels via the dipstick, and there is no visible oil level fluctuations.

There is no white smoke from exhaust and no mayonnaise like build up near oil filler cap.

Your input would be greatly appreciated.

Thanking you,
Vip.