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We have all had repeated problems associated with the poor design of the Polo G40's crank case breather blocking, the only way the crank case can vent when this happens is via the dipstick. When this happens then the oil from the sump gets blasted out all under your bonnet. There are many other associated problems when this happens i.e. poor power, rough ideling, and engine oil seals weeping. Etc.

The oil breathers on G40/60 engines are fed back into the intake system of the car to be burnt off to keep the cars conforming to emission regulations. The down side of this is that oil vapours lowers your petrol octane rating when it is mixed in the cylinders with the oil vapours. Oil is not as volatile as petrol and the effect is the explosion that pushes the engines piston down is not as violent which equals less power. Oil vapour also encourage the engine to 'Pink', when the engine 'Pinks' then there is a sensor on the engine 'Knock sensor' that detects this and retards your ignition timing to prevent pinking happening again. Again this retarding of the ignition timing by the ECU reduces power.

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how does a catch tank stop under fuelling?

So the ideal would be the pipe from the rocker to the catchtank then the catchtank outlet to a brether thus stoping pinking etc?

Two ways of doing it, running it back in still giving the vacuum in the rocker cover or blank off the vacuum but make sure it has ventilation

So there is only 1 feed to a catch tank and no need for a return back to the inlet?

Its saves ventilating the oil back into the inlet. Catch tanks are universal

Can anyone here explain what it does?
can any catch tank be used on any car?:thumbs: