I believe the on you saw was the Dexos approved one. It should be very good for almost anything. It says something like 50% synthetic.
'03 Regal GS L67: PP 5w30/FU3980
'99 Grand Prix L36: QS HM 5w30/STP 3387A E-core, Filtermag
'07 LaCrosse L26: PG 5w30/ProSelect 21040
ASE L1 MT