I've never had to replace an oil plug o-ring on a Ford. Had a 2000 F150 for 11 years. My '88 Ranger had a plastic "crush" ring and I think I replaced that once in the 12 years I owned that. But if you've got another car, go to a hardware store when you remove the plug and buy another o-ring to keep "murphy's law" from biting you in the a$$.
