Why does my engine burn oil?

Explanation continued in here, ICE (internal combustion engine) has been around for over a hundred years. Since the last oil embargo in the eighties governments decided to try to limit the amount of fuel being consumed by the engines. Later the EPA (environmental protection agency) started enforcing CAFE (corporate average fuel economy) to force the manufacturers to reduce the fuel consumption of the automobiles. Car manufacturers had to pay penalties so at the first opportunity the manufacturers decided to start with a clean sheet of paper immediately.

BMW N52 Engine

In the case of BMW it was 2006 with the E90 platform and N52 engine which was first time ever was designed and build with ultimate efficiency, the first of their new iteration of the efficient dynamics slogan.

Naturally the fuel economy standards kept getting more strict so they enacted accordingly which brought us to the new turbo era of the N55 and N20 engines. Let’s go back to the question why does this modern engines burn motor oil way more than the previous models decades ago?

This is all due to the maximum effort to provide fuel efficiency at the highest possible level.

How does all this work?

The N52 introduced the valvetronic system, the N55 introduced a refined version paired with twin scroll turbocharger and direct fuel injection. This all helps the ICE to operate at it’s highest efficiency level at any operating conditions. Naturally all the internal components has been reduced to the bare minimum and every component has been redesigned for minimal friction.

This is where the oil consumption comes in to the picture, by reducing the piston rings to the bare minimum, and reducing the piston ring tension to the same minimal pressure. The piston rings if just ever slightly get carboned up by infrequent oil changes or poor quality motor oil, just by topping it up cheap oil will jam the oil ring and the engine will start to consume more and more motor oil burning it up in the combustion chamber.

BMW N55 Pistons

Here are some relevant pictures of the N55 piston, as you can see the rings are extremely thin and the oil ring tension is next to nothing.

N55 also has a variable pressure oil pump to further reduce the internal load. Additionally the camshafts are hollow and the engine has been specified with a light weight motor oil to reduce the pumping losses even further. If you look closely you can see the rings are like stairs looking at them from the top down which showing the compression ring protruding out the most. The oil scraper ring in the middle is less so, and the oil ring at the bottom sticking out just barely which accounts for the least amount of ring tension.

Maintenance with The Best Lubricant

To make this jewels of engineering last some considerable time you need to give it the best possible care. Maintenance with the best lubricant you can afford and that should give you minimal oil burning and maximal peace of mind.

This is as always, a double edges sword, the clients want maximum power, the manufacturers are there to sell cars, and the government wants efficiency. It’s a difficult fight, a kind of tug of war to have your cake and eat it too, so to say.

I hope this helps, any question, how may we help? Call us for more details. Telephone: 905.795.0419

Related:

More info on, why car’s engines might burn oil.

The importance of proper oil changes

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