Oil changes have gotten more expensive as the Iran war has restricted imports of the raw ingredients used in motor oil, according to NPR.

Although the U.S. is the world’s top crude oil producer and produces a significant share of gasoline, diesel, and jet fuel, the country remains largely dependent on the Middle East for group III base oil, used in motor oil blends.

Since the war’s start on Feb. 28, the price of the base oil used to make synthetic motor has “more than tripled to record levels,” Amanda Hay, an analyst with the market insight firm Independent Commodity Intelligence Services, told NPR.