Oil Disappearing!?

[Deleted member 106115]

MK4 1.8T FR - 80,000 miles.

I'm having to keep putting a few 100ml in every 500ish miles.

Funnily enough I think this has started happening since my last service, in which I told my mechanic to use some 5w/30 fully synth Castrol Edge that I'd bought.

No oil spots under any of my parking spots, can't find any leaks underneath or in the engine bay from admittedly a quick look.

I think it must be burning off?

I read on another thread that a 5w/40 that meets VW spec might be better?

Anyone encountered a similar problem before?

Thank you!

 

[R3k1355]

Isn't your car fitted with an engine undertray??

If so the oil will land there and then spray allover the underside of the car, if it's leaking around the back of the engine you might not even be able to see it.

Jack the car up, remove the under tray and inspect the engine.

 

[Deleted member 106115]

I've checked the under tray as I too thought it may be collecting there, but nothing.
As I say, I don't think it's leaking.

 

[Deleted member 106115]

Perhaps replace PCV valve?

 

[RUM4MO]

I don't know what form the oil separator takes on the 1.8T engine, but when my wife's old 2003MY Polo with a 1.4 BBY petrol engine started gobbling too much oil, I did check the PCV just by blowing through it both ways - it seemed okay, so I replaced the oil separator which cost a bit because it had a motor fitted to it - but it did stop the oil being gobbled up!

 

[Deleted member 106115]

Thanks for the input mate.

I bought the PCV valve anyway, it's worth a shot for a tenner and a few jubilee clips

 

[Deleted member 106115]

Well, I replaced the PCV valve a week ago today but alas... no difference.
I've had to top up 150ml this morning.

 

[R3k1355]

If it's burning it you should be able to spot it being thrown out the back.

Have a mate drive behind you on a clear road and mash the throttle.
If it starts belching out a blueish smoke then you've got conformation it's burning the oil off.

 

[Deleted member 106115]

Deffo can't see any smoke when I boot it.
Turbo seems perfectly healthy too, no whining, boosts well, no smoke.
Hmmmmm.

 

[cheshire cat]

I wonder if you only need 150ml are you filling to the max? I rekon never a good idea unless you're starting a long trip try keep ing it @ 1/2-3/4 and see what happens. Rum4mo what was the motor for on the separator?

 

[RUM4MO]

Sorry for the delay, I am guessing that the motor on the air/oil separator works either like the PCV or with the PCV to control the volume of air being drawn through this separator at high vacuum conditions, so if it was faulty, too much air would be drawn through the separator and so take too much oil into the engine.

 

[britishsligean]

Interesting I think I will try a new pcv on my 1.2 had enough of loosing oil and finding no evidence

 

[RUM4MO]

Just to clarify what I was up to when I replaced the oil separator.

Wife had a 1.4 16V Polo late 2002, ie 2003 model, it started using too much oil, I checked as many other things as I could, what really annoyed me was that the engine was pinking under normal load, so I had to use 98 Ron fuel to stop that, one theory was that any petrol engine that pulling oil into itself would be effectively running very low Ron level fuel from the oil petrol mix, so this made me eventually chose to get a new oil separator ordered in, that was a good guess as it stopped that engine using oil for the remainder of the time we ran that car, ie the next couple of years or so.

I have never ever heard of these oil separators causing any problems so it was a shot in the dark for me.

Edit:- you can give the PCV valve by blowing through it - sucking back through it, it should act as a one way valve.

 

[Deleted member 106115]

I wonder if you only need 150ml are you filling to the max? I rekon never a good idea unless you're starting a long trip try keep ing it @ 1/2-3/4 and see what happens. Rum4mo what was the motor for on the separator?

I never overfill, always keep it bang in the middle

Anyway, it's off to the garage for a quick check later so hopefully m'lad finds something.

Fingers crossed it's not all in the intercooler