So, when I bought my 97 s420 the first thing I did was check/replace all the cam oilers. Which means removing the valve covers. I replaced with new ones, and torqued to the appropriate torque. But now they leak, I've since then replaced them twice, being sure to install properly, and even "upgrading" to name brand gaskets (I've used the Reinz ones most recently). Still leaking. So, anyone have any thoughts? should I use some gasket seal?