Phillips 66 refines crude oil into gasoline, diesel and other fuels, and also operates midstream pipeline and storage assets along with a chemicals business run through a joint venture with Chevron. Like other independent refiners, its profitability depends heavily on the crack spread between crude oil costs and refined product prices, a margin that can swing significantly with seasonal fuel demand and refinery maintenance schedules across the industry. The company's midstream and chemicals operations provide some diversification beyond pure refining economics, since pipeline fees and chemical product sales don't move in lockstep with refining margins. Phillips 66 was spun off from ConocoPhillips to separate the downstream refining and marketing business from ConocoPhillips' upstream exploration and production operations.