I just found out today that GM no longers carries the EOS.... nice.

  Correction... Gm reinstated EOS under new part # 88862586 and looks like doubled the price to about $21.  ZDDPlus sounds like a better deal.

Did you guys not see the post on the first page of this thread with the new Castrol Syntec formulated for classic cars with more zinc?

Use nothing but Amsoil 5w40 or in a pince Mobil one 5w40.  The amsoil is formulated for the now ultra low sulfer diesel engines with extra friction modifiers for them.  It goes in the the 77, 82, the 01 s-10, the 07 scion tC, 73 dodge powerwagon plow truck, 1995 chevy 1500 plow truck, 1987 k-15 blazer plow truck, 01 geo tracker plow truck, 2001 chevy montie carlo, 2007 ford mustang.  Only oil I use, and you can go 7500 miles or 6 months if you want.  works very good on the vettes that are parked for half of the year.