Date: Sun, 5 Jun 2011 09:49:13 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Motor oil - Re: [VANAGON] Spooked!
In-Reply-To: <9FE645A0-284F-4FED-94E1-7EE203AAE3B1@eoni.com>
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The Mobil 1, 15w-50 is still a high zinc oil according to its marketing and
spec sheet. At 100C it has a higher viscosity than a straight 40.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Jim Arnott
Sent: Saturday, June 04, 2011 8:33 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Motor oil - Re: [VANAGON] Spooked!
Reposting with a title that will make sense in the archives.
Jim
On Jun 4, 2011, at 10:06 AM, David Beierl wrote:
> At 11:09 AM 6/4/2011, Dennis Haynes wrote:
>> With today's modern oils there is no reason to have to go to the
>> straight 40 for any temperature. I don't even know straight weights
>> are available with the latest specifications. 20w-50 or 15w-50 will
>> work just as well.
>
> But you agree that 15/20W50 is correct oil for *all* WBX in cool to
> very hot temps?
I would, with a caveat.
In the case of motor oil, newer is not better. As engine technology has
advanced, motor oil specifications have also advanced. The 20W50 GTX today
is a significantly different product than the 20W50 GTX that was on the
shelf when these VWs were new. One of the major differences that directly
affects us is the reduction of certain additives that were designed for flat
tappet engines. Primarily zinc dialkyldithiophosphates (ZDDP). Do not use
engine oil with the "SM"
rating. Or, if you're going to use engine oil with the "SM" rating, use a
zinc additive that will maintain proper ZDDP levels.
Quoting wikipedia, "The main use of ZDDP is in anti-wear additives to
lubricants such as greases, gear oils, and motor oils, which contain about
1%. For applications in oils for gasoline engines, zinc and phosphorus
emissions could damage catalytic converters and have had their quantity
reduced in standard formulations.[3]. Reduced ZDDP oils have been cited as
causing damage to, or failure of, classic/collector car camshafts and
lifters with flat tappets which undergo very high boundary layer pressures
and/or shear forces at their contact faces, and in other regions such as
big-end/main bearings, and piston rings and pins."
A quick Google will take you to way more info than you want. Just let it be
said that less (or no) ZDDP in the current crop of off the shelf motor oil
is NOT good news for us.
Personally, I use Shell Rotella T synthetic 5W40 in every internal
combustion engine I own. From the F350 to the 4 stroke string trimmer.
<http://forums.pelicanparts.com/porsche-911-technical-forum/435355-zddp-shel
l-rotella-t.html
>
This is a decent examination of the issue: http://www.ttalk.info/Zddp.htm
Jim