The answer is low friction, read narrow and thin oil rings with miniature holes-slots on the ring are the answer.
Traditionally the lower oil rings were responsible to bleed and scrape off the excessive oil which in turn got returned to the oil sump. The worst is the twin turbo V8 engine code named N63 with all the thermal load coming at it from the turbo chargers between the two banks.
The motor oil goes thru a significant heat stress, furthermore carbon build up made worst by the extended oil change intervals and lighter weight oil all contribute to the oil rings not being able to do their jobs properly.
As they say a picture is worth a thousand words, if you look at closely the piston’s picture above, you will see the miniature horizontal slots are closed, clogged up shut so the oil will be drawn up into the combustion chamber and burned off in the combustion process.
It’s worth to note the valve seals are also marginal in this particular engine again due to thermal overload, the seals get baked to rock hard and the oil gets sucked in thru the cavitation of the components. The only viable cure is frequent oil changes. We recommend 5/40 grade motor oils and the occasional oil flush also recommended to reduce the carbon build up at crucial places.
We use LM professional oil flush to clean the engine, (engine flush) which is made and tested in Germany, in extreme cases the LM motor oil saver can be used temporarily to soften up the hardened valve seals as a cost effective alternative to major engine repair.
If you have any further questions we will be happy to answer them in person .
Thank you for reading and all the best from Techmax.