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<div class="moz-cite-prefix">On 5/24/2020 5:05 PM, Bob Johns via Fot
wrote:<br>
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<div>Someone was wondering when detergent oils were
initiated. I grew up right down the street from the Kendall
Refinery, and the addition of detergents was a big deal.
The detergents addition to old curded engines was a problem
as the curd could-would break loose and plug up the oil pump
screen. Any way, as I remember the switch over was
1951/1952 period. It is hard to find non-detergent these
days in the better grades of oil.</div>
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<p>The problem was not just plugging up oil screens. Engines of the
time used babbitted bearings, which were sealed in place with
paraffin-soaked wicking and similar materials that became
carbonized as the hot metal was poured. Detergents dislodged all
that carbonized material and, oops!, what little oil pressure such
engines had went away.</p>
<p>Detergents were introduced when manufacturers upgraded to shell
bearings (which were greatly refined during the war years in
aircraft engines). Detergents tended to keep particles suspended
in the oil, which minimized the chance of them becoming embedded
in shell bearings, which was not so much a problem with babbitt
metal. The tin in babbitt metal was soft enough (and thick
enough) for them to get pounded down so they didn't stick up much
from the surface, thus minimizing the damage to often unhardened
crankshafts. The layer of soft metal in shell bearings is very
thin, so the prospect of something getting stuck in them and being
available to wear the crank required rethinking the oils used.</p>
<p>I suspect that the changeover to detergents was accompanied by
the same sorts of problems that the changeover to synthetics
presented. If the engine is designed for the new oils, no
problem. If it wasn't, well, <i>caveat emptor </i>(my father,
IIRC, blew up two engines in his `46 Plymouth in the space of
eight months around the time detergents became available). In the
late `70s, I remember reading some horror stories about engines
converted to full synthetics that burned bearings because the
synthetics ran out of the bearings a lot more quickly, with an
attendant loss of oil pressure. Around the same time, I worked
with a guy who raced snowmobiles along with his brother. He
thought he'd try Mobil1, thinking he'd get another horsepower or
so. First time out, burned a bearing. But, his engine had some
hours on it, so they tried it in his brother's sled the next
weekend, which had a fresh engine. Burned a bearing. Engines
designed for the stuff ultimately had tighter clearances and
higher-volume pumps. Still remember some nitwit Navy lieutenant
screaming at me that "jet engines used synthetics," so why
couldn't he use it in his Toyota Celica (this after complaining
about noisy operation only after he converted to Arco Graphite,
which at the time was something like 0W-15... in Florida, in the
summertime--its hot viscosity was less than water). Trying
patiently to explain that it's fine if it's designed for that oil
and pointing to the owner's manual just didn't work....</p>
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<p>Cheers.<br>
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<pre class="moz-signature" cols="72">--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....</pre>
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