Abstract: A process for recovering hydrocarbon oils and hydrocarbon oils containing dissolved additives from filter cakes produced by filtering such oils using a siliceous filter aid.A small amount of a release agent, up to 2 cc per gram of filter cake, is slowly added to the filter cake with agitation to prevent formation of a release agent phase and then a further quantity of release agent is added to the resultant mixture with gentle stirring and the final mixture is then held quiescent at elevated temperature until an oil phase separates. The oil phase is removed and the remainder of the mixture is filtered to separate a release agent filtrate and a filter cake consisting mainly of filter aid.