I've been running 20w50 Napa oil with a zinc additive the last couple years in my BB. This spring I went to 15w50 Mobil 1. With the Napa oil the gauge would sometimes spike to 80-90 and idle hot at 20-25. With the Mobil the thing will not go above 75 and it hot idles at 40-45. Just something I thought I'd add in here from my experiences.