High oil usage

[TheAngryDog]

Is 3/4 of a litre of oil considered OK for a 2001 134k miles M5 for doing less than 500 miles? That is what mine has just done which is much worse than my old pre face lift car.

Apparently when I am going passed people they can see the puffs of blue smoke.

Seems excessive to me?

[ds666]

I seem to remember that BMW suggests 1 l per 600 miles is acceptable. Does seem high thou and blue smoke in good.

[M5 London]

I believe BMW stated 1L per 416 Miles if I remember correctly.

Calculated from the below :

1.5L per 1000KM

1L per 666KM

1L per 416 Miles


So you are currently consuming at a rate of 666 Miles per Litre (500 Miles per 3/4 Litre). So within tolerance.

If it was me I'd have a quick look at both your Oil Separators and associated tubing. If these aren't functioning perfectly you will be burning more crankcase vapours than allowing it to convert back to oil and returning to the oil sump.

Next thing is to check the valve cover gaskets by pulling off the spark plug covers and inspecting for any oil pooling in there.

Edited by M5 London on Saturday 27th February 12:41

Edited by M5 London on Saturday 27th February 12:44

[TheAngryDog]

The hoses going to the plenum are fine as they were replaced not so long ago. I'll check the spark plug covers. Thanks.

Just seems high for a face lift engine. My pre-facelift was a litre to around 3k miles.

[M5 London]

TheAngryDog said:

The hoses going to the plenum are fine as they were replaced not so long ago. I'll check the spark plug covers. Thanks.

Just seems high for a face lift engine. My pre-facelift was a litre to around 3k miles.

Yep cool !

Hoese are important but have you cleaned or replaced the actual Oil Separators ?

Items 1 and 2 on here : http://www.realoem.com/bmw/enUS/showparts?id=DE92-...

Also if either hoses 9 and 10 are blocked oil will not be returned to the sump.

Most people just change out 14 and 15 which is good but not the whole deal as it were.

[TheAngryDog]

I don't know if they were done tbh, I reckon they weren't though

[TheAngryDog]

Do you have any recommendations for cleaning them?

Thanks.

[TheAngryDog]

Spark plug areas are dry.

[M5 London]

TheAngryDog said:

Do you have any recommendations for cleaning them?

Thanks.

I think first check they haven't been internally damaged in any way (unlikely though). Then spray copious amounts of carb cleaner to it until it flows clean carb cleaner out of both ends.

[TheAngryDog]

M5 London said:

TheAngryDog said:

Do you have any recommendations for cleaning them?

Thanks.

I think first check they haven't been internally damaged in any way (unlikely though). Then spray copious amounts of carb cleaner to it until it flows clean carb cleaner out of both ends.

Cheers, I'll strip it out next weekend and run a tin of carb cleaner through them

[HoagieLomax]

Your oil use is ok for enthusiastic use.

How old is the oil? New stuff burns less.

[TheAngryDog]

Oil was changed last year in October. About 5k miles ago.


Just had the plenum cover off. There's a thin film of oil in there but no pools.

[M5 London]

TheAngryDog said:

Oil was changed last year in October. About 5k miles ago.


Just had the plenum cover off. There's a thin film of oil in there but no pools.

Thin film of oil in the Plenum is fine mate.

[TheAngryDog]

So looking like Rings then?

[M5 London]

TheAngryDog said:

So looking like Rings then?

Do you predominantly drive urban or motorway ? What is the mix ?

Do you engine brake a lot ? This really increases oil consumption. Further highlighted by having your mate follow you whilst you engine brake from high speed and then blast on the throttle immediately....should see very clear blue oil smoke.

To finally dismiss everything please inspect the oil return pipes from the oil separators heading to the sump. Very difficult access and easier when you have the T Stat off. But these sometimes clog up or even crimp themselves, thus not allowing oil return to the sump and more oil vapour is burnt off as its recycled through the plenum. Having the thin oil film is fine, but does prove that oil vapour is entering the plenum where most should be separated by the separator and recycled back to the sump as oil.

Having said all of the above, I wouldn't sweat it. Some E39 M5s just drink oil. BMW state that 1 Litres use every 416 Miles is their limit and you are much better than that at the moment.

[Pip1968]

I had a pre facelift for some years and it initially burnt a lot of oil (around the acceptable limit figure but as time went on improved a lot to the point where top ups were less frequent. I found more oil was consumed on long autobahn drives ~ 100 to 120 mph.

Pip

[hoppo4.2]

A few years ago i bought pre facelift one that had started to smoke.

Turned out to be vanos units which turned into a big rebuild the story is on hear somewhere.

Any way in theory a simple fix.

It got to the point that it looked like a car with a failed turbo the smoke was that bad on lift off.