yup, need new struts, in fact, not sure if you got new ones when you installed your Eibachs, but normally, that is the recommended proceedure, always get new struts with new springs. this is recommended for a number of reasons. the old struts have a built a slightly worn "memory" of where they normally ride on the strut shaft, now they are riding in a different area that is not as worn and this is either causing more wear to the teflon or poly seal in the strut or it is causing the seal to leak where the original wear was. then there's the possisibility that the coils have too much rebound for an older, used shock to handle and the seal is just not up to the task of handling all that extra pressure, and leaks. just some possibilities.