could anyone explain the meaning of the terms on bottles of motor oil?

i was given a bottle of '0W 30' for the fabia vrs when i got it new - have seen other threads suggesting VW specific oils - what do the above terms actually mean? summat to do with how lubricating they are and how long they stay that way?

would it make much difference at all if i used different oil in the engine or even mixed oils?

:confused:

Steve have a look here:

http://www.chris-longhurst.com/carbibles/index.html?menu.html&viscosity.html

Word of caution, your brain may end up like scrambbled egg

thanks for that- looks like i have oil which is ideal for the swedish climate - i spose it gets similar here in the winter (or this summer actually for that matter!)

would this oil be to the standard of the VW oils on other threads or is that a different kind of specification with regards quality rather than temperature-specific viscosity?