If you are seeing STEAM from exhaust then it indicates water, NOT oil. Is it loosing coolant? If so take out and examine spark plugs they should be a chocolate brown colour if any are clean this is where that cylinder is effectively getting steam cleaned with the coolant entering. Another thing to do is to check header tank for signs of "oily water" or the presence of mayonnaise on the oil filler cap.

White smoke can also be caused by a sick turbo.

What HG do you have and what is spec?

Martin