This is somewhat dated, so keep it mind. Several years ago I recall reading about internal engine corrosion in two stroke engines that used full synthetic oil compared to mineral oil. I don't remember the type of synthetic or if it was brand specific, but the synthetic at the time did not have the anti-corrosion properties of mineral oil. I am planning to switch over to full synthetic (Poulan Pro is on my short list ) . I would think the corrosion issue would be resolved by now , but wondering if any one knows the latest on this.