oil consumption E39 2001

-every car I've owned that has used oil has without exception done so for a reason, and its never been a good one.

- I'd be slightly worried if I used a pint every 1000 miles in any engine.  In a few cases I've been able to strip out the engine and find out what the problem is and sometimes its just wear and tear, sometimes the rings just never bedded in (still a dark art), and sometimes its just a mistake.

-there are only a few places oil can go;

1) Down the valve guides- typically a puff of smoke on morning start-up. Nothing in itself to worry about until you get a 'gunge monster' on the valve stem that stops the engine from breathing. But ask yourself why either the guide is worn or the seal has failed. The latter can indicate that the engine and/or the oil has run too hot, and the former can indicate that you have top end lubrication problems. (On one engine that mysteriously used a pint of oil every 500 miles, I found that some genius had decided it would be a really good idea to stamp the inlet valve part number in the stem where the seal wipes over it...d'oh...)

2) Past the oil control rings (ring/bore problem)

3) Out through a hole somewhere (and crankcases run under slight negative pressure on most BMWs so quite big holes high up in the engine don't leak especially badly). You will see oil under the car wherever you park it regularly if the leak is at all bad though.

4) Oil burnt as a mist through overpressured crankcase. Typically piston rings don't seal, piston blow-by increases, and then oil vapour/mist (which  on many BMWs is vented to the inlet air hose between the AFM/MAF and the throttle butterfly) just gets burnt at an ever increasing rate. You don't tend to see smoke with this one for a long time.

Item 4 is potentially an engine killer. Even if you don't run out of oil, the oil in the sump is continually being degraded by rubbish that is blowing by the pistons, and this can cause the oil to fail to lubricate properly well before it is due to be changed.  Modern 12000+mile oil change intervals and inherently 'thin' (eg.0-30W) oils don't help here.

- If the engine uses oil, the oil goes  very black very quickly after it has been changed, and the oil smells 'bad' on the dipstick (compare with some in the sump of an engine that doesn't use oil) 1/2 way through its life then suspect item 4. The 'cure' is either to get the engine fixed, or to change the oil much more frequently than is normally recommended.

-I typically change the oil at 2/3rds the recommended interval on any engine with over 100K miles on it, as any engine wear (and there is bound to be some rather than none) means the oil will similarly be degraded more quickly than normal. Older engines in many cases get fewer oil changes through neglect- actually they probably need more.

-The manufacturer's recommended oil change interval is only OK if the engine is working properly and isn't worn. If this isn't the case then you probably need to do something different.

cheers

Thanks Brucey,and indeed thanks to all who replied to my problem so far.

I havent made up my mind yet what to do about this....

will wait and see what others have to say. as the car is still under warranty ( not BMW..Idependant ) the last thing I want is some have baked mechanic  havin a go !!!!!!!!!!!

Heres the latest, for anyone interested.

The oil consumption test revelled that the engine is using 2.2litres of oil per 100km which I have been informed is very high (I would have never guessed) The car is going in for a week on the 2nd august to be stripped and investigated to determine what the problem is, at this stage they expect abnormal wear to be the cause.

If this is the case and the oil use is down to abnormal/excessive wear then despite not being under the original warranty any more, bmw will cover all costs (which I'll think you willl agree is damn decent of them) if it is due to misuse then I have to pay (time for a re-morgage) I have given the go ahead as i am confident that it has not been abused (see next paragraph)

As far as people saying that it is the way the vehicle is driven when new that seems to play a part, I must disagree, my car has been owned by my dad from new, never thrashed or mistreated, run on a 50/50 mix of unleaded/super and fully dealer serviced regardless of cost (company car), basically it has been very well looked after

I'll let you all know the outcome.

All I can add is.....RTFM.

I was horrified to see the "Normal" oil consumption figures as listed in the owners handbook.  I thought it was a mis-print or an error, but really, it couldn't have been.  German!  100 decimal places of average!  It will not be wrong.

For the record I am using half a litre every 650 miles (1 week).  I am burning a bit, but not so any smoke is showing.  It's me Valve guides in pots 2,4,6.  I wire brush the brown-crusty-crud off those spark-plugs on a weekly basis.  When my weekly mileage gets to a normal 180, I am expecting to do that only every month. 

To Brucey.....

WRT my problem (2 posts up) do you reckon a really thick oil could assist?

I have always dropped my oil every 6K, and nearly always used the non-branded oils, as recomended by the experts in good garages.  Branded oils are 60% marked up for the name.  (The oil bible website backs that up too).

I must have worn valve stems/guides, if the neoprene seals had gone, then the (Last three oil changes) addition of Wynns Stop-Leak should have softened that neoprene.  But it aint.

I do not intend taking the head off to mend this, as you know - head off means empty wallet.

Modern engine?  Well, compared to R kids original Cooper S (Git!), I suppose mines modern.  (1989 (12 valve) E34 2 litre with a real coil and dizzy cap)

So, your advice still stands?

Compressed air....with an adapter screwed into the spark-plug-ole?

What a good idea!

A bit of a bummer if yer rings have gone too, though.    Which you don't find out about until the valve drops.  And it's always on the pot with the piston at the bottom!

I will mention this idea to my Engine mender (I do the rest).  This could give a lot more life to my car.  I was thinking of binning it next year.

Had an oil change done 2200 miles ago used mobil 1,done some long hard runs uk and Ireland, by the dip stick im expecting to add a litre shortly seems the change in oil brand maybe  paying off thanks again for all of your replies, real good info in there,will keep yous posted