Breaking in a new engine is a balancing act. The need to protect the engine
with enough lubrication and at the same time not so much that the rings
don't have a chance to seat in the cylinder bores. Starting a rebuilt engine
with new rings and freshly honed cylinders has the disadvantage of
additional initial frictions that are only there for the first few hours of
the engines life. When I assemble any engine air or water cooled I increase
the piston skirt to cylinder clearance from the stock new measurement of
.0015ths  to .003ths. The tight skirt clearance on the new stock piston and
cylinder sets has always been used to allow for wear of the cylinder and
piston BUT this is historical not modern day fact. The vanagon water cooled
engine for example shows less than .001ths wear on the cylinder in most
cases after 150K plus miles. I also finish hone the cylinders with a finer
stone than the factory and then I do what's known as a plateau finish this
removes then tops of the scratches or peaks of the finish. My experience is
that this extra attention to the cylinders helps make sure the cylinders are
straight, round and have less friction (heat) on start up with no compromise
in longevity with less of a chance of piston scuffing or ring damage in the
first hours of operation.
The oils I recommend for engine break in depend on the outdoor temps the
load that the engine will see in the first 1000 miles
If you can keep the van off the highway for the first 1000K then I suggest
10/30 in the winter and 10/ 40 in the summer if you must drive the van on
the highway for more than a few minutes than you need to go straight to a
20/50.
For oil changes I would like my customers to change the oil after the first
1/2 hour of running and then at 300 miles and again at 1000 miles.
Dennis is monitoring is oils condition so that can extend the intervals of
oil changes but I don't consider switching to synthetics as a substitute for
oil changes and that is what most people want when the inquire about
switching to synthetics

I always change my oil before a trip and get high on the REAL thing and
what's that you ask ?
a full tank of gas and a clean windshield

prepping to go north to Canada and still going faster miles an hour with the
radio on

I remain
Bob Donalds
Boston Engine

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