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


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BMW 535ix low oil pressure warning

The perils of using the wrong method trying to correct the problem. We received this BMW 535ix with low oil pressure warning related to a known issue which started from a common oil leak the filter pedestal and cooler gaskets.

This considered a common “maintenance ” type of work on the BMW N55 engines. We charge $450.00 to replace both gaskets, and only viable part is the revised genuine gasket, it will hold up better in the future.

The technician working prior on this engine, (the vehicle has been towed from a another garage), had this “clever” idea to just apply silicone sealant.  Unfortunately in a futile attempt, that made the leak actually worse, which resulted in the classic usual result.

When the belt gets soaked long enough with motor oil, it will shred and gets grabbed by the crankshaft and whipped up into a ball or cord and rubber.  It gets pushed thru the front crankshaft seal,  the timing chain will grab it and the whole thing gets ingested by the engine.

You can imagine what happens with a bunch of cord and rubber, when it gets shredded internally by the timing chain, it creates a complete disaster. Now to fix this,  the entire bottom below the oil pan needs to be removed, like axles, differential, the steering rack control arms, the engine mounts and the sub-frame assembly to expose the oil pan.

Naturally the top engine cover, the valve cover has to come off as well, including all the high pressure fuel lines and rail and so forth. The rather mundane gasket replacement turned into a partial engine overhaul, where we have to remove the oil pump and must inspect the connecting rod bearings for excessive wear, due to oil pump suction pipe restriction by the belt pieces.

We went from a $450.00 dollar job to a 6 thousand dollar engine recovery and major resurrection. They tried to fix the oil leak, replaced the front seal the wrong way, as well as by removing the center bolt holding the timing chain sprocket in place by friction.

Needless to say the camshaft timing was moved as the vehicle would need to be set up with a special jig to be precisely timed for proper operation. Worth to note, the center bolt must be replaced, as it’s a single use stretch bolt, or it could cause major engine damage.

We have documented all the problems, detailed with plenty of pictures.

Things that you can see in the photos below happen, when  individuals try to repair or maintain BMWs without  proper knowledge, expertise and tools.

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BMW N55 Engine Repair

I appreciate my general practitioner or dentist for what they do, but I would not want to get a brain or heart surgery from either one of them. They are a specialists in their own field. This is why they call a specialist,  a specialist. They have expertise in their own field and the proper tools and experience to perform a task to the best of their knowledge.

Any questions, how may we help? Call us for more details: 905.795.0419

Related: Information and the key features of our services and programs. Type of service that we offer, specializing on fine European cars.