On Sat, 31 May 2008 01:04:22 GMT, Jeff <kidsdoc2000.TakeThisOut@hotmail.com>
wrote:
>> Baloney.
>> The tolerances are virtually the same as they were 10-15 years ago.
>
>Actually, they're not. The tolerances are smaller, because, with robots,
>engine makers are able to have smaller tolerances.
No, they are able to maintain CLOSER tolerances. They can produce
finer finishes, more repeatably. There are less "high spots" or "tight
spots" which means the engine does not require a complex breakin - but
the specified clearances are virtually the same in today's engines as
they were in "precision" engines 30 or more years ago.
>
>> The low viscosity oil is for fuel economy, almost exclusively.
>
>Gee, that means that with lower viscosity, there is lower friction.
>Lower friction is good for an engine.
No, not necessarily. There is less VISCOUS friction. That is good for
economy, and as long as everything goes according to plan (like that
EVER happens for long) it is good for the engine. However, what is
good for fuel economy is NOT always good for engine life. A thicker
oil film provides more protection - to a point - as does an oil with
EP additives (like Zinc) which are no longer allowed because WHEN, not
if, the engine burns some oil it poisons the catalytic converter.
Thick oil is less prone to burning - so thicker oil with zinc is just
as good for the converter as thin oil without.
Saying today's engines last longer because of the thinner oil would be
a faulty observation because so much more has changed - not just the
oil viscosity, or the oil composition, but the fuel composition as
well. Lead free gasoline is likely the largest contributor to longer
engine life due to the fact phosporous and other similar compounds are
no longer required to keep the lead suspended and avoid lead buildup
on valves, guides, pistons, and ports. This keeps the acidity of the
crankcase in check, making everything last a bit better.
>
>> And using 5W30 in place of 5W20 has NO detrimental effect on
>> lubrication because when it is cold, where lack of oil flow due to
>> viscosity would be a problem, they are virtually IDENTICAL. The oil is
>> thicker cold than either of them are when warm (and thicker than a
>> 5W50 would be when hot as well)
>
>Yet, there is more friction with the higher viscosity oil.
No more "friction" ANd precious little difference in pumping loss.
>
>One thing you have not accounted for is that today's oils are better
>than the oils of 10 or 15 years ago.
Not necessarily better, but definitely different. They are better in
some ways - but that still has not ballanced out the loss of EP
performance due to removal of zinc and other metallic EP agents.
>
>> The ideal oil, as far as I'm concerned, would be a 5W50 or 0W50
>> synthetic (only because non synthetics are almost impossible to
>> produce with that wide a viscosity rating and still be "oil".)
>
>And this is based on what evidence?
Which? That it would be the best, or that it is difficult to produce a
non-synthetic with that broad a viscosity range and still be "oil"?
The (long chain) polymers used to enhance viscosity index DO reduce
the "oilyness" of oil somewhat. That is a known fact
0W50 synthetic oil DOES exist - that is a fact. 5W50 non synthetic is
extremely rare if it exists at all - and that too, my friend, is a
fact.
If you understand oils at all you know that a 5W50 is still thicker
when cold than it is when it is hot. An SAE5 oil cold is thicker than
an SAE50 hot. So a 0W50 or 5W50 oil still thins out when hot.
The "cold" number affects cold start oil pressure and the spped at
which lubrication is acheived on a cold start. The "hot" number
affects the film strength(indirectly) and the oil pressure and
lubrication of the engine when hot (and under load) and has NO EFFECT
AT ALL on cold start lubrication.
The ONLY "problem" with an oil with a high VI is a fraction of a
percent difference in fuel economy.
>
>> They use low viscosity oil now because they CAN. The thin oil today
>> does a better job than thin oil could do 15 years ago in many ways -
>> but is still not as effective as a slightly thicker oil could be.
>> ** Posted from http://www.teranews.com **
>
>Evidence that a thicker oil is better, please.
40 years of experience is all I have as evidence, but there is a lot
of research out there that backs me up.
If thin oil is better, use straight 5 weight, or even kerosene or fuel
oil.
Today's manufacturers are specifying the thinnest oil they think they
can get away with to coax that extra 1/10% fuel economy out of their
engines. If they use the thin oil to qualify the engine, the MUST,
under American law, require/reccomend that oil for every-day use.
>
>Jeff
** Posted from
http://www.teranews.com **
>> Stay informed about: Higher Oil Viscosity? 
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