A method for preparing the first component of a two-component room temperature-vulcanizable (RTV) silicone composition comprises (a) preparing a filler/oil masterbatch by (i) adding an unreactive silicone oil and untreated, aggregated filler particles to a mixer; (ii) adding a filler treating agent such as an organosilane, a polyorganosilane or a silazane to the unreactive silicone oil/filler mixture; and (iii) mixing the unreactive silicone oil/filler mixture and treating agent under conditions sufficient to breakdown the aggregated filler particles to an average size of less than about 300 nm for a time of less than about 24 hours to form the filler/oil masterbatch; and (b) adding said filler/oil masterbatch to a reactive silicone oil.