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Date:    Wed, 7 Feb 2007 06:35:00 EST
From:    Frank Condelli <RAlanen@AOL.COM>
Subject: Re: Castrol, QT, 5W50

Mordo, you missed one very  important part of that post.  20w50 is standard
oil and 5w50 is full  synthetic.  There is no 5w50 standard oil so one of
the solutions to cold  weather starting is to use synthetic oils that come
in 0w50 and 5w50  configurations.  It's the 50 part of the oil that the
waterboxer needs to  have a long healthy life.  The low part of the oil
number is to aid in starting at cold temperatures.  Now, all that said it is
not always advisable to switch an old engine over to full synthetic as it
"may" cause  softening of the seals and therefore induce oil leaking
problems.  Some  gamblers do it and win some loose.  The lower the miles on
the engine the  better chance you have.

Cheers,

Frank  Condelli
>
Frank,

The synthetics are not as bad as they initially were.  Early synthetics did
not have sufficient seal conditioner, but all synthetics have gone through a
lot of additive and formulation changes over the years including improved
seal conditioners.  The bad press from "inducing leak" anecdotes is still
there on everyone's minds, though.  My own experience with using a synthetic
in an old, oil dripping Ford Motorhome that sat a lot is that adding
synthetic and then driving a few hundred miles actually "conditioned" its
dry seals -- no more drips.

The "high mileage" formulations have even more conditioner, and are even
less likely to make an old car leak.  Mobil has a "high mileage" synthetic,
but it only goes up to a 10W-40.  Their regular synthetic is available in
15W-50, as you know.  But I'm now convinced, like others, that an older
vanagon engine deserves 50 weight when hot, so I haven't tried a
high-mileage one yet.

Darn, I told myself I wouldn't get into YAOT! <grin>
(Yet Another Oil Thread!).

Rich