Discussion
Can anyone help me identify the problem that I have with my S3? I noticed the dipstick oil is a milky colour and there is a milky sludge in the oil filler/breather.
I have only been using it for short trips lately, could that be the reason or is it a sign that the cylinder head is leaking coolant into the oil? The car has done 65K.
I have only been using it for short trips lately, could that be the reason or is it a sign that the cylinder head is leaking coolant into the oil? The car has done 65K.
I agree, take it for a run to get it proper warm, check it again and if no worse then take her for a good hot blast and you should find the milkiness will disappear, HOWEVER if there is a lot of the stuff about in your engine already then I would change the oil asap and before a good blast as you dont want your bearings lubricated by water now do you 
K
ps - would you mind if I added you to the S3 Owners list ?
K
ps - would you mind if I added you to the S3 Owners list ?
I was under the impression that milky oil was a sign of a head gasket failure - but I think the give-away is if the coolant hoses feel under pressure when the engine is running (test by squeezing the hose with your hand).
Someone with more mechanical knowledge may blow this theory out of the water though.
Someone with more mechanical knowledge may blow this theory out of the water though.
The milky emulsion is water mixed in with the oil. It's perfectly normal for engines to have water in the crank case due to blow-by past the pistons, and this will typically evaporate when the engine is hot and then condense under the rocker covers as it cools, ready to give you a fright. This time of year, combined with short trips, you could easily have large quantities of emulsion and I wouldn't be too concerned to see that.
To start with, I suggest you look at the coolant. If you have emulsion or scum in the coolant then you definitely have a problem and should not run the engine until it's been fixed. There is never any good reason for the coolant to be contaminated.
But if the coolant looks fine, and the oil pressure is OK, I'd take the car for a drive and get it thoroughly warmed through over an hour or so. This will boil off the water and blow the vapour out of the crank case breather. It may seem alarming to run an engine with emulsion where there should be oil, but remember that unless you have put gallons of water in the crankcase through a massive leak, all you have is emulsion clinging to the sides of the crank case and sitting on top of the oil; the pump draws from the bottom of the sump and will still be immersed in nice clean oil. It's when there is so much water that the whole oil volume turns to emulsion that you will damage the engine - and if it's in that condition you can be pretty sure the damage is already done.
To start with, I suggest you look at the coolant. If you have emulsion or scum in the coolant then you definitely have a problem and should not run the engine until it's been fixed. There is never any good reason for the coolant to be contaminated.
But if the coolant looks fine, and the oil pressure is OK, I'd take the car for a drive and get it thoroughly warmed through over an hour or so. This will boil off the water and blow the vapour out of the crank case breather. It may seem alarming to run an engine with emulsion where there should be oil, but remember that unless you have put gallons of water in the crankcase through a massive leak, all you have is emulsion clinging to the sides of the crank case and sitting on top of the oil; the pump draws from the bottom of the sump and will still be immersed in nice clean oil. It's when there is so much water that the whole oil volume turns to emulsion that you will damage the engine - and if it's in that condition you can be pretty sure the damage is already done.
I thought oil floated on water
I would go along with the "short trips" theory.
Also, I suggest that before you take it for that long run, you first check that the breather is actually working - it's incorporated in the oil cap at the rear of the nearside rocker cover - take it off and clean it in paraffin (NOT petrol!) - it might also help to clean through the long hose that goes from the cap to the back of the air filter - take it off, stick a long bit of wire through, tie a tiny wad of cloth to the wire, and pull it back through.
The long run won't help if the breather is already blocked!
Also, I suggest that before you take it for that long run, you first check that the breather is actually working - it's incorporated in the oil cap at the rear of the nearside rocker cover - take it off and clean it in paraffin (NOT petrol!) - it might also help to clean through the long hose that goes from the cap to the back of the air filter - take it off, stick a long bit of wire through, tie a tiny wad of cloth to the wire, and pull it back through.
The long run won't help if the breather is already blocked!
Gassing Station | S Series | Top of Page | What's New | My Stuff