Completely mysterious oil loss problem

[Dan1978]

Hi,

I wonder if anybody else has had (and hopefully solved) a similar issue. My first generation Mini Cooper S JCW is using frankly ludicrious amounts of oil and seems to have been doing it since I had it - I suspect why the last owner sold it, though I can't prove that...

I've taken it to 3 garages now; a the Sytner mini garage, my local garage and a local engine specialist. They all say the same thing -

The car is not leaking oil - there are no drips and the engine looks as clean as a whistle and the car is not burning oil - because there is no smoke coming out of the exhaust.

However, the car is using a liter of oil approx every 300 miles - meaning it can easily get dangerously low during a long car journey. Apparently BMW consider usage of up 1 litre per 1000 miles to be acceptable (WHICH IS JUST PLAIN LUDICRIOUS), but either way, my car is burning up oil at over twice that rate.

There simply has to be something wrong with the engine, but nobody seems to be able to diagnose what. The last garage said they could try replacing the piston rings, but without any obvious sign the car was burning up the oil they can't guarantee it'll make any difference!

Has anybody got a clue what could be going on here?

[Dan1978]

I did wonder whether the cat converter could be burning up the oil and disguising the smoking? But the garage said apparently not...

[Readster]

The oil is going somewhere Dan...burn, leak? into the gearbox?
The garages should be able to advise you.
John

[Dan1978]

Hi, thanks for the response... that's kind of the problem. I've taken it to 3 garages and they can't advise. The first garage (Mini Service) first said my sump gasket needed replacing (which they did), but the car burnt another half litre of oil (1 quart) so I took it back. They investigated and said they couldn't see anything wrong and the car must've just 'used' the oil that had disappeared.
They suggested I drive it around a while and see if the problem continues.

It did continue, but I'd kind of lost respect for the first garage so took the car to another hoping that I'd find somebody competent to look at my car. The second garage said that it wasn't leaking and must be something internal and recommended an engine specialist I should take the car to.

The engine specialist looked the car over and said again they couldn't see anything wrong, but agreed that the oil consumption was absurd. They said they only thing they could think of was that my piston rings were shot, but they said they couldn't understand why there was no smoke. They then phoned Mini, who told them that consumption of around 1 litre per 1000 miles was to be expected and their mechanics hadn't ever had to replace the rings on a mini engine in all the time they'd been fixing them. This 3rd garage basically said they could replace the rings (at a cost of about 1.5 k), but they didn't want to do it, because they couldn't offer me any guarantee that it would fix the problem...

So here I am, my car is mysteriously using so much oil that I can go from half way on the dipstick to 'min' in a 250 mile car journey and nobody can find anything wrong with my car!

[techlab2k]

Hi, silly question, does it get to a minimum level or does it just keep using oil until the warning comes on?

[Dan1978]

Hi, no the light has never come on (at least not in the time that I have owned it), because I check my oil and top it up before it gets that bad. Before I knew I had a problem I was only checking about once a month and at one point I had to put in close to 2 litres to get the oil to about half way on the dip stick. Since then the oil has never dropped below min because I check it obsessively!

[marque]

Hi
If you don't have any visible leaks
I would say first of all check all your crank case ventilation system it easy and costs nothing make shore everything is clear and not blocked and the breather valves are in the right place and the right way round
Get a leak down check carried out on the cylinders that will tell you condition of your piston rings. This will tell you if you burning it past the rings.
If there is no smoke on start up your valve stem seals should be ok
I would also see if you can get a scan gauge or similar and drive the car to see the real time water temp, the hotter the water temp the more oil you will burn as the engine gets hotter than optimal running temp . My MCS runs about 90 to 95 deg c ish as a rough guide
If your car is running hot it could be a few things badly worn supercharger belt, water pump, thermostat or the water pump drive gears in the supercharger.
The Gears suffer from lack of oil because there is no bmw service intervals on the SC it's Fit and forget. But Eaton say they should be serviced regularly.
The gears and bearings wear out and the water pump them is not driven correctly so the car runs hot and burns oil because its hot and the engine can over heat and cause damage due to lack of coolant flow
Remember just because the water temp gauge it's half way it does not mean its ok
It is a token gesture do not trust it

[SteveM3]

Tiny amounts of oil are dumped into the intercooler which is why you see many tuners sell oil catch cans to stop this. Check the inside of your intercooler as best you can, yours may have a fault and be dumping unusually large amounts of oil into the intercooler. To quote from the Alta web site "Ok while your motor won’t explode tomorrow, it is an excellent idea to get a catch can in ASAP! The MINI Cooper S Supercharged engines are prone to accumulation of an oil sludge mixture forming inside the intake tract, intercooler, boost tubes etc.. This is a result of crankcase pressure and inefficient combustion. While this is normal operating procedure, it is a hindrance to making higher horsepower and increasing engine longevity. Oil vapor is forced out of the cylinder head and redirected through vacuum hoses into the intake stream. The oil vapor then condenses onto the inside surfaces in the intake system. This is especially prominent in the intercooler core. A thin film of oil coating the inside of the intercooler will insulate the air to air exchange and lower the ability of the intercooler to cool the intake air charge. Plus this oily vapor also carries dirt from the combustion process and places it in areas of the engine that were previously clean."

[Dan1978]

Quote: Originally Posted by SteveM3 (original)

Tiny amounts of oil are dumped into the intercooler which is why you see many tuners sell oil catch cans to stop this. Check the inside of your intercooler as best you can, yours may have a fault and be dumping unusually large amounts of oil into the intercooler. To quote from the Alta web site "Ok while your motor won’t explode tomorrow, it is an excellent idea to get a catch can in ASAP! The MINI Cooper S Supercharged engines are prone to accumulation of an oil sludge mixture forming inside the intake tract, intercooler, boost tubes etc.. This is a result of crankcase pressure and inefficient combustion. While this is normal operating procedure, it is a hindrance to making higher horsepower and increasing engine longevity. Oil vapor is forced out of the cylinder head and redirected through vacuum hoses into the intake stream. The oil vapor then condenses onto the inside surfaces in the intake system. This is especially prominent in the intercooler core. A thin film of oil coating the inside of the intercooler will insulate the air to air exchange and lower the ability of the intercooler to cool the intake air charge. Plus this oily vapor also carries dirt from the combustion process and places it in areas of the engine that were previously clean."

Hmm, that is about the only thing none of the garages I've spoken to have ruled out. Where would this oil go though? Would I expect to see smoke, or dripping? I've gone through about 7 litres of oil, so it can't all be just sitting in the intercooler/boost tubes etc. can it?!

[SteveM3]

Quote: Originally Posted by Dan1978 (original)

Hmm, that is about the only thing none of the garages I've spoken to have ruled out. Where would this oil go though? Would I expect to see smoke, or dripping? I've gone through about 7 litres of oil, so it can't all be just sitting in the intercooler/boost tubes etc. can it?!

Most will go into the engine and be burnt but I don't know if it will be visible as blue smoke. I think there was a modification to the crankcase breather hose but really a MINI dealer will know more than me. Removal of the intercooler is simple and if it is oil free it will give you peace of mind it's not being lost by that route.

[Dan1978]

Quote: Originally Posted by SteveM3 (original)

Most will go into the engine and be burnt but I don't know if it will be visible as blue smoke. I think there was a modification to the crankcase breather hose but really a MINI dealer will know more than me. Removal of the intercooler is simple and if it is oil free it will give you peace of mind it's not being lost by that route.

Mini dealer is effing useless. First time I took it in they said they couldn't see anything wrong and that the car maybe just 'used' the oil. They said to drive it around for 500 miles and come back. So I did - 500 miles and over a litre of oil later I took it back... they said, well it isn't leaking it, so it must be burning it. They said is I paid them another £80 they'd do a cylinder leakdown test, but said there's no point unless I am prepared to pay for a new engine because they don't fix internal problems. I basically got the impression they couldn't be arsed diagnosing the problem and would rather just drop a brand new engine in and charge me 5 grand.

The next garage I took it to said there was little point in doing a pressure test anyway (is this true?) because it won't tell them much of anything. They don't know what is wrong either, but are trying to find me a second hand engine - good luck to them as it is a JCW... they also said to me 'well it isn't leaking it, so it must be burning it' and said the other option was to replace the piston rings and valve seals which 'should fix it, because there's not much else it can be'. Obviously it is an expensive job and I'm not going to pay them to do it on the basis that it 'should' fix it!!

Sadly, I'm a bit clueless with cars past the basics so can't check this stuff myself... maybe I just need to find a competent garage!?

[Dan1978]

Oh, got a OBD dongle and took it for a drive to find out my engine coolant temperate. It was running around the 90 degrees mark, so the engine isn't running hotter than it should be.

[marque]

Hi ya

Glad it's running around the 90 deg mark its a good start

If you want to know the Heath of your engine you need to start with a leak down test.
It's not pointless, your piston rings can be worn and you may be burning oil past them but not notice it in your mirror or visually.
at higher rpm as the SC start to raise the compression/pressure in the cylinder. if the rings are not sealing properly it will increase pressure in the crank case which will then push more oil vapour in to the inlet via the crank case breather system then gets burnt. And then the cycle starts this will then start to gum up the rings then they don't work as they should then you oil control ring starts to fail which means you start to burn oil and it goes on.
If your oil control rings are gummed up you can try using seafoam in your engine oil for a few hundred miles and take it easy then do an oil and filter change it may free them up and help

Never rule out anything start with the basics
If it does not smoke on start up in the morning or left for a long time the valve stem seals are most probably ok.
Leak down test will help you see if the piston rings but not you oil control rings are ok
Oil control rings
Then you in to crank case ventilation system

Before going down the engine change route you need a definitive answer if you change the engine and you still have the problem from a £10 part you will not be a happy bunny.