Like other equipment makers, John Deere is gradually loosening its stance on biofuels. In a recent “clarification” notice, the Moline, Ill.-based machinery company says it will honor warranties on Deere engines burning 20% biodiesel blends, but notes that 5% blends are still “preferred.” Blends must meet voluntary ASTM D6751 specifications. Users also are “strongly encouraged” to purchase biofuels from BQ-9000-certified suppliers. A list of those companies is located at Deere was the first domestic off-highway engine maker to use a biodiesel blend as a factory fill.