You should be running deisel grade oils. Standard 10-40 Valvoline is not good for your valve train. Either run deisel (Fleet grade) or the "race" oils, or add a can of Comp Cams' additive or GM EOS. I also only use Wix produced oil filters. They are about $6 each, from Car Quest, Napa, and various retailers. I also run CQ 15w-40 Fleet oil in all my cars with flat tappet cams. It's like $1.29/qt by the case IIRC.