In mid-June, "Oyashio" was assigned as escort for cruisers in projected further Indian Ocean raids, but the operation was cancelled by the time she reached Mergui in Burma, and she was reassigned as escort for the cruisers and to Balikpapan and the Solomon Islands. During the Battle of the Eastern Solomons of 24 August she was part of Admiral Kondō's Advance Force, but was not in combat. During September, "Oyashio" was used for patrols between Truk and Guadalcanal, and in October began operations as a "Tokyo Express" high speed troop transport to Guadalcanal. These operations continued to early-February 1943. During the Battle of Santa Cruz on 26 October, she was assigned to Admiral Kurita's Support Force, returning after the battle with and to Shortland Island. During the Naval Battle of Guadalcanal on 13–15 November, "Oyashio", launched a torpedo attack against the American battleship . After the battle, she returned with the cruiser to Rabaul. On 21 November, she sortied from Rabaul to assist the destroyer . During the Battle of Tassafaronga on 30 November, "Oyashio" torpedoed the American cruiser .