Re: Synthetics???/(LONG answer)

[JGriffJ@aol.com]

In a message dated 95-10-30 18:05:06 EST, you write:

>Hate to bring up an old topic again...
>
>I just changed the oil in my car (90 20V) and replaced it with the Mobil 
>1 synthetic oil.  5w30 (winter coming and all...)
>when I started the engine, cold, it read the usual 5+ bar. After it 
>heated up a while, it read +-3bar at idle. Now I thought the whole damn 
>point of synthetics is they dont lose their viscosity over the 
>temperature range. Its no better than the old dino I used to use. am I 
>missing something here??? Did I forget to carry the 2?? :)
>
>BOb
>
This is a  long one, so strap in....

My car does the same thing, and I am using Amsoil's 10w30 100% synthetic. It
is not a problem though, and it is normal. The heat will thin them both out,
but there is a substantial difference re: the protection offered. In fact,
here is some info from Red Line Oils and Amsoil that may answer your question
(or confuse you... or bore you...):

RED LINE......
"In order to manufacture a multigrade petroleum, say a 10w30, a 10w oil is
thickened with a polymeric plastic substance much like STP. This enables the
oil to flow like a 10w oil when cold, but appear to be an SAE 30 when
measured at the high temperature (100 degrees C). The problem is that the
high temperature testing is done in a tube at the equivalent shear of a very
low RPM. At high RPMs, a 10w30 multigrade petroleum will appear to have a
viscosity between a 10 and a 30, and at a VERY high RPM the viscosity will be
a 10. A synthetic generally does not thicken as much at cold temperatures or
thin as much at high temperatures [ie. more stable] as a petroleum oil, so
large quantities of unstable thickeners are not required. The advantage is
that at high RPMs and high temperatures, a synthetic 10w30 can actually
provide thicker oil films than a straight SAE 30. However, caution must be
advised when thinking about synthetic 5w40 and 5w50s. Here significant
amounts of the thickeners used to make petroleum multigrades must be used so
that the high-shear viscosity will provide the equivalent to a petroleum SAE
30.

The superiority of synthetics lies in the fact that a 10w30 synthetic can
provide the high-shear protection superior to a 20w50 in the bearings and
cams, while providing a much lower viscosity on the cylinder walls and in the
ring pack. This lower viscosity produces more power and also better
efficiency and fuel economy."

AMSOIL....

To illustrate RED LINE'S text above, Amsoil states in their brochure (while
showing a glowing red exhaust manifold) that:

"Amsoil Engine Oils endure 64 hours in this engine with less than an 8%
change in viscosity. That's High-Temperature Thermal Stability!! No
conventional motor oil can say that. The American Petroleum Institute (API)
allows viscosity increases (thickening) of up to 400% in this Sequence IIID
test; but Amsoil doesn't."  And on and on....


So, most petroleum oils will thicken and turn into sludge when exposed to
great amounts of heat; they break-down and clog things up. That's why they
need to be changed so much more often. Synthetics don't, thereby allowing
longer drain-intervals.
And can you believe that the API allows a change of 400%? Wow!! Just think of
that the next time you buy a petroleum oil.

Well, I hope this has helped. I have researched synthetics quite a bit (and
no, I DON'T sell any products or have any vested interest in any specific
company!! No flaming please!) and wouldn't use anything but. However, I do
have preferences. And as I have posted before, I do not like Mobil 1 (and
others on this list have agreed), since it seemed to not hold pressure very
well. It seemed to thin out more (I really noticed a difference on my oil
gauge when I HAD to add a quart once... and that was just one quart that I
added!!). But enough about my preferences....

So Bob, I don't think you need to concern yourself. Instead, feel good that
you are using a synthetic, [even IF it is Mobil 1 :-) ] and not a petroleum.
Your car will love you for it!!!

If I can shed some more light, please feel free to e-mail me.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                    Jim Griffin
                 jgriffj@aol.com
                     92 100S
      Titanium Grey/Black Leather

A ccelerate U nless Death is I mminent
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~