Your engine will not run as well as it is capable of if it isn't properly broken in. I've heard that synthetic oils reduce friction so much that they will prevent your engine from breaking in. I've also heard that Corvette engines are run in at the factory, then delivered with synthetic oil. I started useing a synthetic blend in my rebuild at about 4000 miles and there are no problems whatsoever. My wifes Nissan has had Mobil 1 in it since 30k and still runs like new at 99k. So, go for it, just be sure you are fully broken in before you do.... <img src="/forums/images/graemlins/kewl.gif" alt="" />

you will know it when the rings seat...it's almost an instant increase in power. took a little under 100 miles with EB's good moly rings on my engine.