Those are all old rumors. Hell the new John Deere snow thrower I just bought has synth in the Briggs from the factory. Many cars have been shipping that way from the factory for years.

 

I read an article in the HOG magazine that was written by the company and it said you can use synth from new. People used to say you needed to run the engine in for a few thousand miles first. Nowadays engines are machined to far higher tolerances so they don't need running in as much as they used to. I was going to use synth from the 1000 mile service but the dealer said that it was a waste of money because the standard mineral oil is fine so I've stuck with that.

If you live in a hot climate I'd guess it would help the engine run cooler.

 

Read this- http://www.harleyhelp.com/oilbrand.html - at least read the bottom section of it about breakin and why.