well sometimes you can split them with out any special tools, but if they are bonded together good you might need a case spliter, dont go jamming a screw driver between the cases, you will damage them and it wont seal where you put screw driver ati would try to put some yamma bond on the case where its leaking first, this way you dont need to split them. just clean area very well, use rubber gloves so the oil from your fingers dont contaminate the area that is leaking.