One possibility for the oil fire is that PT boats had smoke generators on many of the hulls to provide a screen for quick withdrawal. A boat could be out of fuel and still have oil in the drums.
PT-109, PT-162, and PT-169 were ordered to continue patrolling the area in case the enemy ships returned.[11] Around 2:00 a.m. on 2 August 1943, on a moonless night, Kennedy's boat was idling on one engine to avoid detection of her wake by Japanese aircraft when[12] the crew realized they were in the path of the Japanese destroyer Amagiri, which was returning to Rabaul from Vila, Kolombangara, after offloading supplies and 900 soldiers.[13] Amagiri was traveling at a relatively high speed of between 23 and 40 knots (43 and 74 km/h; 26 and 46 mph) in order to reach harbor by dawn, when Allied air patrols were likely to appear.