[symby]

I have a large volume of oil which needs to pass through a buchner filter. However, the volumetric flask is too small. So, I need to somehow remove the filtrate from the flask as it fills to allow the process to happen without stopping the filtration and pouring the oil into another container.

Is there such apparatus out there? If not, any ideas how I could do it?

Thanks in advance. 

[kriggy]

You need something like this
http://www.sigmaaldrich.com/catalog/product/aldrich/syna841420?lang=en&region=CZ

filter it into separatory funnel, then you close the vaccum, open the funnel, drain the filtrate, close it and apply vacuum again. But you need some kind of valve to close the side adapter vith vacuum while not letting air going through it