Just what is an oil catch tank for?

[Skifledanabit]

As above really, what are they? What are their purpose? Are they even worth it?

[grinder]

i have no idea , but im sure the concept is that the dirty oil it caught in the can rather than going back into the sump to be re-used ?

or something along those lines

[Mir]

Oil Catch Tank is used for catching the Oil (which is mixed with petrol) which exits from the engine through the oil exit port (breather) which is build in either at the back of the rear engine plate (in case you have a 3 rotor) or which is build just under the oil filler neck.
 
Mir

[Skifledanabit]

So... Kinda pointless then...?

[Mir]

So... Kinda pointless then...?

Umm not really! It actually keeps your engine bay clean and also help the globe from pollution. If you are fussy like me, it also helps you to keep a close eye on your side seals, because if you have a stronger side seals, less compression will escape from them (which will mix with an oil and come out).
 
Mir

[B.Martin]

They\'re worth it on some cars skiff, but I would spend your money elsewhere mate

[Skifledanabit]

I wasn\'t even thinking of buying one, I just keep seeing them around and wonder what the hell they\'re for lol

[B.Martin]

Oh fair one, well Mir just explained. Failing that Google it :Giggle

[Prof]

Used to catch evaporative emissions (from crank case pressure). On the stock rotary plumbing, these emissions are fed back into the intake through the PCV - that weird black plastic thing that sits behind the oil neck.  On the TII we have 2 such pick ups - one from low down on the filler neck / centre iron, and the other one is from the top of the oil neck, it T\'s in with the charcoal canister outlet and into the induction pipe.
 
The idea of the catch can is to take the oil / petrol / water and hold it in the tank rather than let the engine eat it.