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Re: oil viscosity

To: HMENTZEN@aol.com
Subject: Re: oil viscosity
From: Ken Streeter <streeter@sanders.com>
Date: Thu, 02 Oct 1997 18:31:52 -0400
Cc: triumphs@Autox.Team.Net
Organization: Lockheed Sanders, Inc.
References: <971002180451_-127336157@emout14.mail.aol.com>
HMENTZEN@aol.com wrote:

>  Right now I'm using 20/50 weight oil in my Spit. I drive
> the car all winter in MA. Its less than 5 miles to work each
> day and I'm wondering if a lighter weight oil would work
> better in cold weather situations.  TIA!

I would highly suggest switching to at least 10W40 for
the winter in MA.  At some point of chilling, 20W50
becomes too thick to be pumped by the oil pump.  From
what I can find out, this is about 10F for 20W50
Castrol GTX.  5W30 Castrol GTX should be good down
to about -15F.  For best protection against hard
starts, and extra wear from jello-like oil, switch
to a synthetic.

There is an excellent article by Ed Hackett on the
VTR WWW pages which covers this topic:
  http://www.vtr.org/maintain/oil-overview.html

My conclusions from that article are that I would
consider the following to be minimum temperatures
for starting a car without an engine block heater
with various oil viscosities.  (For cold temperatures,
only the first number matters.)

"Natural" Oils:
    20W     10F
    15W     0F
    10W     -10F
     5W     -20F

Synthetic oils of the same ratings have much lower
"pour" points, and can be used at much lower
temperatures.  From what I can see from the charts,
synthetics are good for about 30 more degrees:

"Synthetic" Oils:
    20W     -20F
    15W     -30F
    10W     -40F
     5W     -50F

--ken
VTR WWW Maintainer -- http://www.vtr.org
'70 & '74 TR6 Daily Drivers  

-- 
Kenneth B. Streeter         | EMAIL: streeter@sanders.com
Sanders, PTP2-A001          | 
PO Box 868                  | Voice: (603) 885-9604
Nashua, NH 03061            | Fax:   (603) 885-0631

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