The 402R has a roller cam. Roush says
oil is a personal preference. They have a Roush branded fully
synthetic oil that was developed for their engines by Valvoline. He said it had a higher
zinc content which he said was better for the engine even though it was a roller (?)
If the majority of experts on this site agree to switch to
synthetic this might be a choice but I'd like to hear what the latest science and recommendations are from you guys. Thanks.