you can either believe it works better because you have seen the evidence first hand or someone you trust has told you it is better. My mechanic swears by it and I have seen were components in my turbo diesel have less wear than other trucks similar to mine in age and usage. I have been a firm believer in maintenance to lessen the severity of repairs and using the best quality products just makes sense to me. If you get 150,000 miles on a motor and someone using synthetics gets 200,000 miles then the small cost of good maintenance practices and synthetics seems to be more cost effect in the long run.
Art