Half-synthetic break-in

[yamaha1470]

My friend called me and told me that he had got a 400ex and broke it in and was going to do an oil change on it. He called the dealer to find out what they put in it and it was oil that was half synthetic. Now that he broke in the engine with that could it have messed anything up? Why in the first place should u not use synthetic? What about the half synthetic that he used?

Thanks

[ridefastrgetoff]

Breaking an engine in with partial synthetic oil should not be a problem; the only question I would have, was it fully broken in ? It sometimes a bit longer with parasynthetic than with full petro oils. Petroleums are much more abrasive than synthetic so that's why they are the preferred lube for break-ins; that's also the reason why synthetics protect so much better after the initial break-in period. As for will it hurt your engine ? Shouldn't have any negative effects if it was fully broken-in ! As an FYI, NEVER USE FULL SYNTHETIC FOR BREAK-IN PURPOSES ON 4 STROKE ENGINES !