A good engine it is! My father ran one up to 223000. My sis had one, and I had one in a Corsica. Anyway, they all seemed to do fine on 5W-30 or 10W-30. The highest mileage one did best with MaxLife 5W and 10W-30. The second did best on Durablend 10W-30. Yes we were Valvoline people, till reading BITOG. The Corsica did very well with Castrol High Mileage 5W-30, regular Castrol, SuperTech and the best MPG was with Chevron Supreme 5W-30. It seems to be a pretty tough engine.
---In the winter 5W-30 and summer 10W-30 would be my suggestion. Something higher in Moly helps if there is piston slap. I did notice these engines seemed to like the 10W-30 best.