Sounds just like a HD service manager. When I put a cam plate on the counter my HD service manager asked me "what's that thing". USE SYNTHETIC EVERYWHERE!!!
Most use syn oil for added protection against wear and/or viscosity breakdown due to heat. If you don't race or get caught in traffic on hot days you don't really need it, but I use it just the same. do a search and you will find at least 50 pages of facts, opinions,and myths on this very topic!