Date: Thu, 4 Oct 2007 10:07:27 -0700
Reply-To: Don Hanson <dhanson@GORGE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson@GORGE.NET>
Subject: Re: Mobil I ... negative..(from digest)
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Hi,
Perhaps it was a coincidence that Mobil One was the oil most often present
in the motor-failures I was personally made aware of. For me, it is easier
to eliminate the possibility of the same coincidence happening to me, again,
by avoiding that particular type of synthetic oil.
Porsche 928 motors are known to have a design weakness (prone to oil
starvation, it was thought) in the #2/6 main bearing, and they often failed
unless this weakness was addressed by cross drilling the crankshaft, by
installation of an Accusump, or by 'dry sumping' the motor. When run at a
track under prolonged left turn high G cornering, stock motors were prone to
seizing up that particular bearing..Many instances of this were noted on our
928 Mailing list...Rennlist... One member undertook to document the type of
oil being used at the time of these engine failures, and by far the most
common oil was Mobil One synthetic..To me, that indicates Mobil One was
perhaps the least effective lubricant...Most failures=Least effective...
So yes, almost all of the 928 motor failures were proven to be
lubrication-related. The two moto engines I blew were also bottom end
bearing failures on relatively new motors..The Dayton Triumph was on it's
first fill of "real" oil after being broken in exactly as prescribed by the
Factory manual, the KTM had about one month of time on it and also blew out
the bottom on what's widely regarded as a 'bullet-proof' very dependable
motor.
Is that "proof"? Heck no...but for me, it is close enough to proof to
make me not use Mobil One and chance another coincidental motor blow up..
I ain't saying it's bad, so don't go all defensive if you love the oil...I
am saying I won't use it any more unless I can't find another brand in the
proper weight, and if I do have to put some into a motor, I change it as
soon as I can find another supply..
Ciao.
Don Hanson
----- Original Message -----
From: "Dennis Haynes" <d23haynes57@hotmail.com>
To: "'Don Hanson'" <dhanson@GORGE.NET>; <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, October 04, 2007 8:49 AM
Subject: RE: Mobil I ... negative..(from digest)
> Was any one of those failures proven to be lubrication related? I mean did
> a bearing actually seize up because the correct viscosity, under proper
> pressure and at proper temperatures oil actually failed to provide a
> lubricant film? Or was it just a coincidence that Mobil 1 was there when a
> valve spring broke or head gasket blew or a piston cracked while the
> engine was being abused? Keep in mind that Porsches for many years are
> known for their ability to keep mechanics employed. You still don't
> regularly see 200,000 mile examples.
>
> Dennis
>
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