Root cause of high oil consumption

[MJK1]

I’ve got a 2012 F10 M5 with 70000 miles. It runs very well without any problem except I find it consumes 1 litre of oil every 2000 miles. This equates to about 0.25% of the fuel consumption which is about 5 times above usual engine design limits. The engine isn’t leaking oil so it must be going down the exhaust. This seems a fairly common problem with these engines, does anyone know the exact cause? The only potential causes I can think of are:-

1. Past the piston rings
2. Past the valve seals
3. Past the turbo seals
4. Crankcase ventilation fed back into the intake

It has a full BMW service history and they use a 5W-30 oil. I’m considering trying a thicker oil as that should reduce consumption, has anyone tried this with any success?

[HXS]

I use Liqui Moly Special Tech LL and consumption is less... I need to add 1 liter around every 5,000 miles

[Craze]

0w-40 doesnt burn too much

But 1l every 2000miles is ok

[Solo_M_Tech]

73k miles and I don't use any oil between changes ( 5k interval of 5w40). Stage 2 tuned.

[BPMSport]

Change the PCV valves. The pre 14 ones were prone to failure. Switch to a slightly thicker weight. This should do the trick.

[M5Rick]

I use 0W40 Edge and it's better consumption than the 0-30 I used before. An even thicker oil is not good for immediate circulation in cold weather i.e. rod bearings.

[AnotherM]

I use 5w30 liquid moly and have never had any oil consumption.

2016 cp 58k miles

[blake6511]

Originally Posted by BPMSport

Change the PCV valves. The pre 14 ones were prone to failure. Switch to a slightly thicker weight. This should do the trick.

Any signs that they are bad outside the oil consumption?

[BPMSport]

Originally Posted by blake6511

Any signs that they are bad outside the oil consumption?

If the car is a 12 or 13, consider it bad. You can remove it to check it for function, but a good tell tale sign is looking for oily residue on or around the valve. They changed the design in 14ish, I always recommend replacing these.

[M5Rick]

Originally Posted by BPMSport

If the car is a 12 or 13, consider it bad. You can remove it to check it for function, but a good tell tale sign is looking for oily residue on or around the valve. They changed the design in 14ish, I always recommend replacing these.

Mines a '13 and there's no residue around the pcv's but they're easy enough to replace.