E30 Zone

Im having a problem with my 325i.On start up Im getting grey smoke and burning oil smell.Oil and water levels are fine, car running fine but appears to be blowing oil through the k&n filter.Obviously its pressurising the system but can someone tell me the best possible place to start looking for a cure.

thanks for all the replies

Check the breather from the rocker cover to the intake bellows.

Thanks chris
Ill give it a go and hopefully it will be blocked