yankees1 - See attached thread from similar discussion on break-in oil from a different forum:
Q: If break- in happens so quickly, why do you recommend using petroleum break- in oil for 1500 miles ??
A: Because while about 80% of the ring sealing takes place in the first hour of running the engine,
the last 20% of the process takes a longer time. Street riding isn't a controlled environment, so most of the mileage may
not be in "ring loading mode". Synthetic oil is so slippery that it actually "arrests" the break in process before the rings can seal completely. I've had a few customers who switched to synthetic oil too soon, and the rings never sealed properly no matter how hard they rode. Taking a new engine apart to re - ring it is the last thing anyone wants to do, so I recommend a lot
of mileage before switching to synthetic. It's really a "better safe than sorry" situation.
Q: My bike comes with synthetic oil from the factory, what should I do ??
A: Synthetic oil is so slippery that it actually "arrests" the ring sealing process before it's complete.
The best power and least wear comes from perfectly sealed rings !! The solution is to change the
factory installed synthetic oil back to petroleum for the break-in period.
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That comes from a bike site, but they noted at the beginning of the article that this applies to ALL 4-stroke engines, car, lawn mower, etc.
That only confuses me more - I know "conventional wisdom" has always been to wait on the synth for at least a couple thousand miles, so what is different now that allows the Corvette, Viper, etc. to run it from the start???
[ 22. December 2002, 13:05: Message edited by: MX5