It was both! ;-)
They require no less than 40:1 Synthetic oil and I was using Amzoil 100:1 because it worked so good on my Brison 3.2 and my 3W engines that I just didn't think it mattered. Well I know now. After I broke the rebuilt engine in on 32:1 Penzoil I went to Mobil 1 MX2T racing oil at 40:1. Just before I sent it back to them for the bearing it was turning a 32X10 Bolly Wood prop at 5800+ RPMs on JMB cans. I know when I switched to stock mufflers it was more. The prop would always go super-sonic in the air if I didn't keep the throttle down.