Good note Dave and filled with tough questions. I'll pass along
some thoughts from which someone wiser than me can reach
conclusions.
Dave Munroe wrote:
> Hi Rick;
>
> Good words of wisdom. Did your research carry you into the conflicting
> requirements of break-in period lubrication vs. lubrication for longevity in
> a fully-bedded engine?
It did not, but I have pondered the issue. More below...
> Having an equal interest in ancient (50's and 60's) two wheeled vehicles as
> LBC's, a common problem is finding a suitable brand of oil that will allow
> the rings to seat while not allowing the bearings to self destruct in the
> process.
The only insight I have seen in this area is to avoid synthetics
as they are just too good and if you have new bearings, you
should be able to 'break in' new rings just by using a thinner oil
( 10W30 ? ). The new bearings are actually coated with a thin,
soft metal (?) coating that wears away selectively causing a 'custom
fit' to the journals. This is minimized with synthetics but should
happen just fine with 10W30. I can't believe that this is actually
metal-to-metal contact. Rather, something kinder and gentler --
but I don't know what.
> The problem, as far as my reading has been able to uncover, is that
> "modern" oils have been designed to lubricate surfaces prepared to a
> production level of finish unheard of when our LBC's were built.
...or unaffordable at the time. I mean, these wonderful little B
engines are just tractor engines. The fit and finish is like a new
pair of work shoes. They aren't 'comfy' until all the bits conform
to one another. Just look at the new engine break in procedure.
It's something like "...don't exceed 2500rpm for the first 250
miles..." or something. But your thought are right on the mark.
You can put a new modern design engine right on the redline
straight out of the box! I once bought a new BMW M3. On the
windshield was a sticker say that I should avoid speeds above
135mph for the first 1000 miles! I laughed out loud.
> The lubricity properties...
Isn't "lubricity" a cool word? Its like "Uvula" in that it sounds
somehow nefarious.
> ...and additive package of modern oils are so good as to prevent
> the surface to surface contact required at the granular level to
> "work-harden" the surfaces in preparation for the long service life we all
> lust after. Hence we suffer long or "never quite" broken-in rings and other
> sliding surfaces in our newly rebuilt units..
work-hardening, while understood in theory, is a topic I
have never had to think much about. Sadly... Yet, I am not
convinced that it is the additives that are creating the better
lubricating properties. Many are there to minimize breakdown,
to buffer heat related reactions and to control viscosity changes.
> The solution is an oil with properties close to those of the oils produced
> and available at the pump 20 to 40 years ago for break-in, and a good,
> modern synthetic oil for longevity after. Problem is, what's a good
> equivalent to an oil from the good-old-days? A cheap, discount shop 20/50?
> got any recommendations?
I recommend, unofficially, a name brand of 10W30 for break in
followed by Castrol GTX (20W50) changed at 3000 mile intervals
WITH a new filter. I don't believe that the tolerances in the B engine
are so close as to gain benefit from synthetic oil -- especially when
you remember that synthetic does NOT swell seals and gaskets so
leaks are more likely.
Probably the BEST solution is to use a good 20W50 oil and change
it and the filter every 3000 miles. Remember, natural oils break down
and loose the lighter hydrocarbons to evaporation. That's why they
become thick and nasty. Change 'em often -- especially in a wonderful,
if low precision, engine like the B.
> Dave
> Puzzled, as usual
You are much wiser than you imply.
best,
--
Rick Lindsay
Diamond Geoscience Research
5727 S. Lewis Ave., Tulsa, OK
Voice: +1 918-747-3456
Fax: +1 918-747-8599
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