September RBOB prices grinded lower during the initial morning hours, registering a lower low in the process. Some traders were concerned by yesterday's negative reversal action, with prices first rallying to their highest level since April 17th but ended with a small loss on the session. Meanwhile, the supply situation in the US gasoline market is showing some tightness along the west coast on reports that Chevron's Richmond refinery could be shut for up to six months.