ConocoPhillips introduced three engine oils meeting the API CJ-4 standard for diesel engine lubes. Each was designed for use with 2007 low-emission engines. Guardol ECT and Kendall Super-D XA are premium synthetic-blend oils for use in diesel engines using exhaust aftertreatment devices; both can also be used in older engines. Fleet Supreme EC engine oil is designed for fleets that seek "economically efficient" oils, the company says.