<VV> STP and the Scerwdriver

[Mark Durham]

JR, the Mobil 1 10w30 has a 10.7 cSt  (10.7 mm2/sec) at 100C
which is right in the middle of the range Richard Widman calls out in his
oil article, I think he says 9.3 to 13 something.
 The Mobil 1 10w40, has a c 14.7 cSt  (14.7 mm²/sec) at 100C, which is
slightly above the range Wichard Widman calls out, but the viscosity lowers
as the oil gets older so, I think the 10w40 would be a better choice.

The 15w50 oil is at 18, way above the range.Technically, you could be doing
damage at startup, however, we have folks who say they have used the 15w50
all an engines life and have 200K miles or more on their unoverhauled
engines. So, whether the full synthetic makes up for the higher csT ratings
in viscosity, by being extra slippery and maintains that boundry layer in
the bearings, who knows. Its your best guess. But it seems to work.

I know that I used to run my engines on 10w40 dino oil for years with no
issues, with regular changes at 3-5K miles.

Mark Durham






On Wed, Jan 4, 2012 at 10:28 PM, Ron <ronh at owt.com> wrote:

> Sounds logical to me.
> RonH
>
> ----- Original Message -----
> From: "Smitty" <vairologist at cox.net>
> To: <virtualvairs at corvair.org>
> Sent: Wednesday, January 04, 2012 9:00 PM
> Subject: <VV> STP and the Scerwdriver
>
>
>  > Smitty Says;  I am not an oil engineer and because of the years since I
> > was
> > in the school I am not even sure of the terminology.  Nor am I sure of
> the
> > application.  But here goes.  When I worked for Philips 66 we who were
> > even
> > remotely involved in sales had to go to schools on the properties of oils
> > so
> > we could sound half smart when talking to customers.  There is a thing
> > called dynamic barrier when oil is pumped between flat bearings and
> > crankshafts.  It keeps the metals separated when pressure is applied to
> > press them together.  If oil too light in viscosity is used the oil will
> > extrude out from between the metals and galling will occur.  If oil too
> > heavy in viscosity is used the dynamic barrier will rip or pull apart and
> > again you will have metal to metal contact.  There is actually a big wide
> > range of viscosity that can be satisfactory but naturally the engineers
> > will
> > specify a median viscosity to provide protection under high and low heat
> > operating conditions.
> > STP is a viscosity improver and in it's unmixed state is very thick and
> > slick feeling.  Slick, not necessarily because it is such a superior oil
> ,
> > but because at low speeds of relative motion its thickness of barrier
> > provides contact prevention between two components.  It might make a heck
> > of
> > a lubricant in a differential but in an engine at 7,000 rpm bearing life
> > would be very marginal.  The point being that there is a lubricant for
> > every
> > application and there is often a fine line between what you can and can
> > not
> > get away with.
> > Which brings us back to screwdrivers.  When you wet a screwdriver bit
> with
> > STP and then try to hold on to it, chances are you will use the same
> > fingers
> > you tried with the conventional oil.  Chances are you will be holding on
> > (pinching) just about the same tightness.  The regular oil with a
> > viscosity
> > of probably 10 to 40 extruded out from under your fingers and allowed
> skin
> > and fingerprint contact with the screwdriver.  What's the viscosity of
> > STP?
> > 100- 120-150?  I don't know but it is going to take a lot longer to
> > squeeze
> > it out for the same skin and fingerprint contact you had with the oil.
> > Chances are your fingers will get tired and your grip will weaken before
> > that happens.  In any event, the holding up a screwdriver with STP in
> your
> > fingers proves absolutely nothing.
> > So maybe I am all wet about all this.  I just hate snake oil salesmen
> >
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