Just bought car.. which motor oil should i use?

Royal Purple 10w-30
Motorcraft or Wixx Filter

I would also change the rest of your fluids when ever you get a used car. Radiator fluid, tranny, and rear.

Don't know where you are located so..

50/50 in cold climates, 80(distilled water)/20(antifreeze) in hot climates along with a bottle of Water Wetter.

Royal Purple tranny fluid
Royal Purple rear end fluid w/ friction modifier

I'am a RP fan but any synthetic will work, just stay away from Penzoil products.

I would get the cheapest oil the parts store has in 10W30 and use that with a motorcraft filter. As long as it has the 'api' seal on it, the oil is fine. The $.97 walmart oil is just as good as the $2 name brand. I would also keep that oil in for a week or so, then be anal and do another oil/filter change.

I run mobil 1 synthetic and a mobil 1 extended performance filter in my 347, but I want good stuff. The filter alone is $11!