What type of oil does a vauxhall/opel corsa b take?

I have a 1998 1.4 vauxhall corsa type b, petrol, with an oil leak, does anyone know whether it takes synthetic or non synth oil or semi synth or whatever and what sort would be best to buy, thanks!|||it would be a 15w40 semi synthetic oil. Comma call it xt 2000