Hi I have a 2002 ford Taurus ohv (not dual overhead) with 2205xx miles I just paid it off and then last night my wife noticed a knocking noise while I was driving, checked the dip stick wiped it off pulled it back out and it was bone dry so i immediately bought 5 quarts of 15w-40 let it run for a while then since the gas was low too when to gas station filled her half up with 93 and some fuel injector cleaner. Since I have drove about 60 mile and still knocking. have read other threads but not sure if it is bearings, or rods, or something? I do know that the knocking is the loudest at ~700rpm (idle or stopped) then almost unnoticeable at ~1000rpm and the not that bad but a little more high pitched at 2300rpm-2500rpm. I know some of the other threads mentioned checking oil pressure how do I check it, also almost positive my oil pan gasket is bad and a friend at work mentioned it may be o-rings since I have a little white smoke but it has done that for a while now (about a year) but no knocking, but could i check the o-rings by compression testing each cylinder. finally another thread mentioned knocking after coolant leaking in a cover and this might be possible as i neglected replacing my recovery tank for about 3 months but finally did. Im no mechanic but I do as much as possible by myself and always change my oil and other work like breaks and heater core and tire-rod ends so i know a little about cars but i dont know thats much if anyone has any advice that would be awesome.