theres a national company called "pirtek" that maintain and repair hydraulic equipment and they use 25ltr containers for their oil. the one based in gloucester where i am let me have as many as needed for free as they have problems getting rid of them. i rinsed them all round with a little de-greaser and flushed out with de- ionised water and the water came out lovely and clean on the windows. i currently have 10 i no longer require, if anyone wants them let me know.