http://www.permatex.com/products/Automotive/adhesives_sealants/sealants/auto_Permatex_Clear_RTV_Silicone_Adhesive_Sealant.htm
I personally wouldn't use any sealer at all, however if you feel you need to use some I would recommend this instead:
http://www.permatex.com/products/Automotive/automotive_gasketing/gasket_makers/auto_Permatex_Ultra_Copper_Maximum_Temperature_RTV_Silicone_Gasket_Maker.htm