Smoking engine ?

[Lynn Eades]

Barry, I suspect you have stuck oil rings. My reasoning is that you have 8 cylinders that are firing and otherwise working. You just have excess blue smoke? (that's a question)
Here's a statement pulled from the net.

Stuck piston rings are caused by carbon deposits in the ring grooves. Hard carbon, a result of poor fuel combustion, virtually cements the rings into the grooves. In the past, the only way to free up stuck piston rings so they seal properly again, was to overhaul the engine.

I see a couple of things that you might investigate:
FTC Decarboniser. This is a pack that comes with a flushing oil.
Marvel Mistery oil.

I've never seen or used either, and there are probably more options.

Assuming you have no other mechanical problems (like broken oil rings?) and you do not want to rebuild your engine, then continuing to use your engine in the same way will only cause the problem to continue or get worse?
I assume that to try and fix this then you need to take on board a change of direction? (an attempt to pull it back from the brink, so to speak)
The reason I suggested you "work" the engine was to try and free the rings. An oil ring is supposed to scrape the oil down the bore and ride the oil going up. therefore it needs to be free to move in the groove. I suspect they (the oil rings) are stuck in their grooves and that your compression rings are still free. If you had one stuck (or broken?) then the engine would probably puff rather than put out a steady flow of smoke?
One of the above additives might fix the problem by freeing your rings, but you will probably need to flush your engine anyhow, because by chemically removing carbon at the rings, will no doubt free up the crap that Richard is talking of.
Having gone through this process (which is not guaranteed) then you have to decide what oil to use. I would then use a high detergent oil, if it were mine, to try and keep the rings clean.

We can all make our comments, but non of us has skin in the game. Only you.
Good luck with what ever you decide.