Synthetic or synthetic blend oil is fine for Honda's. Synthectic's reduce friction, means slight increase in power. I worked for Honda & we did many synthetic oil changes, I'm curious as to your friends reasons why not to use it. I've been using full synthetic ever since the 1,000 mile break-in for the engine. Still runs like its new and now has about 25K miles of abuse.
If the engine is damaged some oil might cover up the problem, while synthetic's make it more noticeable.
http://www.importreview.com/reviews/...0-130valv.html