[Mgs] Syntec 20W 50

[Max Heim]

There is also a lot of misunderstanding regarding how viscosity relates to
oil pressure, and what that actually means. People assume they need a
"heavy" oil to maintain oil pressure. A higher viscosity oil is harder to
pump and may therefore give a higher pressure reading on the gauge, but it
also restricts the rate of oil flow, which may lead to oil starvation at the
bearings. What the bearings require is a continuous oil film -- this is a
function of flow rate, not pressure. The reason we talk about oil pressure
is because this is a property that is easily measured with a gauge -- it
isn't a good in and of itself. The measurement of oil pressure is merely a
crude substitute for the oil flow rate measured at the bearings, which is
unobtainable, from a practical standpoint.

--

Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires



on 6/22/11 8:56 AM, mghirsch at netzero.net at mghirsch at netzero.net wrote:

> You may have a misunderstanding of what the numbers mean.   A number like 5 or
> 50 describes the viscosity, or how well the oil flows.  Usually, the colder
> the oil, the more viscous it is.  Viscosity is dependent on other factors than
> temperature, such as moleular shape, stabilizers, etc., so that every liquid
> has it's own rate of viscosity change.  As an example, the viscosity of water
> varies very little from the freezing point to the boiling point.   Synthetic
> oils may, depending on a number of factors, have a flatter vicsosity curve
> than conventional oils allowing a range lilke 5w-50 or 0w-40 that conventional
> oils cannot match.
> 
> My experience with Syntec has been very good, in fact I run 5W50 year round in
> my V-12 Jag.
> 
> Maynard
> ---------- Forwarded Message ----------
> From: Phil Bates <jello at cableone.net>
> To: mgs at autox.team.net
> Subject: [Mgs] Syntec 20W 50
> Date: Wed, 22 Jun 2011 07:24:57 -0700
> 
> Ok, I edited in my HTML editor, and that's why I lost the content before.
> Oops.
> 
> This thread may have hit the list before - but I found out this week that
> Castrol
> is no longer selling a 20W-50 Synthetic oil (Syntec).  I've been using it in
> my
> Lotus Elan, an Esprit.  I know some british car owners were also using it
> because
> it had higher ZDDP levels than regular Castrol GTX.  Unfortunately Castrol's
> solution is that 5W 50 is the best replacement.  Well, it's not.  A cold temp
> 5 wt
> oil is too thin for my cars, and probably several of yours.  Bottom line is
> that I
> now have my choice of Mobil 1 15W-50, or mail order for Red Line or Amsoil
> if
> I
> want a Synthetic 20W 50.  I can do that - no problem, but a lot of harassment
> to
> me, as I used to pick up Syntec at the local Autozone.
> 
> Maybe if Castrol heard they're losing business to their compititors, they'll
> reconsider.
> 
> For Castrol's comment on the change - see #8 on their website here:
> 
> http://www.castrol.com/liveassets/bp_internet/castrol/castrol_usa/STAGING/loc
> al_asse
> ts/downloads/f/Castrol_EDGE_FAQ.pdf
> 
> I can add that last night I changed oil in one of my cars.  As it was winter
> when I
> changed oil last, I had used Syntec 5W-50.  I did have some concerns with oil
> pressure, but not major ones.  I had purchased enough Syntec 20W-50 for this
> oil
> change before it got discontinued.  I drive 30 miles to work, so my oil does
> get
> hot.  Oil pressure this morning was better.  Although it should be the same
> hot
> (they're both 50 wt hot), I had about 1/2 a bar (close to 10psi) more
> pressure
> before I pulled off the freeway.
> 
> Syntec 20W-50 will be missed, and I will have to go to another manufacturer.
> 
> Phil Batse