Daniel L. Katz wrote:

>dan
>
>to make this convincing, why not switch back to mobil 1 and see if old
>pattern returns, keeping driving similar, of course. incidently, my
>understanding is that new rings do not seat as well using synthetic oil.
>
>dan
>
>
Generally speaking, break-in on a new engine is done with a straght 30
wt.  non-detergent motor oil as a break-in oil . This intentionally
allows more wear of the microsopic contact surfaces on the metals so
that parts seat to a closer fit - "seating in" as it were. Once worn to
closer tolerances multigrade oil - synthethic or otherwise - is put in
to the engine to provde the lubrication in the closer tolerances.

During the break-in period parts tend to "work-harden", particularly
rings and cylinder barrels, and then can no longer "wear in",  so proper
break-in is critical, because if not done correctly, you wind up with an
oil burner and all the oil swappig in the world is not going to help.

Regards,

John Rodgers
88 GL Driver