Tom Webber wrote:

Hello all,  I have a question and would like feed back on the use of
Mobile One engine oil.  Should the engine be broken in using a non
detergent for X number of hours then use Mobile One.  Or can the
synthetic oil be used right off the jump?  All comments are appreciated.
 T.W.

Tom,
I would absolutely begin the engine's life on petroleum after a rebuild.
100% synthetic oils reduce friction so dramatically that engine break-in
lasts a long time.  This applies to products with 5-10% petroleum, like
Mobil 1, as well.

The recommendation most often seen is to run a shortened interval on
petroleum to wash out anything left inside from machining or assembly, then
run a second or third interval until oil use stabilizes (hopefully at

zero).

The second half is about ring seating, though.  (This is an area that I'd
like to hear about from a rotary builder - how do we know when the apex
seals are seated?)

Many cars are shipped from the factory filled with synthetics - nearly all
the European models (VW has had a synthetic-filled drive train since at
least 1988), many Japanese cars, drive trains of many big trucks in the US,
Vettes, etc.  The initial fill of synthetic engine oil in these vehicles
comes at a price, though.  Corvettes with initial fills of synthetic

oil are

taking upwards of 45,000 miles before rings are seating and the engine is
making good power.  Same with big trucks.  Cummins specifies running 20,000
miles on petroleum before switching to synthetics or blends (the best

blends

are only 20% synthetic).  Running a single 10,000-mile interval on

petroleum

and switching to a synthetic blend stretches break-in (including lower fuel
economy and elevated oil use) out beyond 80,000 miles.

Break-in, significant oil leaks, and very dirty/neglected engines are not
the places for synthetic oil.  Break-in due to decreased friction and
lowered wear, leaks from recurring costs, and dirty engines due to the
significant cleaning effects of synthetic base oils (clean 'em first).

Make sure the petroleum used for break-in has detergents - at least API

spec

SB (the current is SL).  The engine needs the detergents and dispersants to
keep things clean.  The non-detergent SA oils should have been off the

shelf

in the late 40s...
Andy

<Mazda mag article snipped>

Just to be precise about it, "break-in" of an engine is referring to the
rings..as in PISTON rings.  Right?  There isn't anything in a rotary that
the engine oil will help "break in".  The shop I work with sends all new
rotary engines out with Mobile 1.

Tom, were you talking about a piston engine?

Mike McGee
VAF Home Wing/EAA Chapter 105 Flyin Coordinator
June 19th, 2004
Scappoose, OR

 
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