Good info here guys! I probably would not have run 40w anyways but I will likely be changing the oil this fall on my Winder and it will get full synthetic 5W-30. I ran the Mobil One 5w-30 for several years in my Attak with great success.
Funny the Penzoil was ranked 1st but yes it's synthetic so different than regular Penzoil..... always stayed away from their non synthetic oil back in the day. Totally different subject but I felt that way with Quaker State too with the waxy paraffin base. I had two vehicles give me trouble with Quaker State with engine sludge build up and I always changed oil and filter every 3,000 miles.