HOUSTON — Jiffy Lube is now offering its customers two new ways to pay for preventive maintenance services. As part of a marketing program with Shell Oil Products U.S., the Shell gasoline credit card for consumers and the Shell fleet credit card are now accepted at most Jiffy Lube service centers. Shell has a 23.1 percent share of the gasoline credit card market, according to the September 2004 issue of The Nilson Report, a newsletter that covers consumer payment systems. Jiffy Lube and Shell have aggressively used credit card marketing programs to retain customers and attract new ones. In November, the two brands began offering a rebate to Jiffy Lube customers who pay for services with their Shell MasterCard credit card. The 5 percent rebate on the first $100 of daily Jiffy Lube purchases is applied to future purchases of Shell gasoline. That promotion is in partnership with Citi Cards, which issues the Shell MasterCard. Headquartered in Houston, Jiffy Lube International, Inc. is a wholly owned, indirect subsidiary of Shell Oil Company.