The present invention relates to a process for desulfurizing heavy oil feedstreams with alkali metal compounds and improving the compatibility of the to stream components in either the feed stream, an intermediate product stream, and/or the reaction product stream in the desulfurization process. The present invention utilizes a high stability aromatic-containing stream that is preferably added to the heavy oil prior to reaction with the alkali metal compounds. The resulting stream resists precipitation of reaction solids in the desulfurization reactors. Even more preferably, the desulfurization system employs at least two desulfurization reactors in series flow wherein the high stability aromatic-containing stream is contacted with the reaction product from the first reactor prior to the second reactor, wherein the first reactor can be operated at a higher severity than without the use of the high stability aromatic-containing component stream.