It is best to use one of the case-bond glues between the cases (These sealers smell like airplane glue when curing). Case-bond is oil resistant and semi drying. RTV/Silicone that smells like vinegar when it cures is not really oil resistant. Over time silicone swells up and looses it's adheasan.
Ultra grey and ultra blue is not a RTV type silicone it is more closely related to threebond 1211.