I think this has been fixed by the synthetic manufacturers.  It was present
with the original Mobil 1 (NLA) but now the synthetics include the seal
additives.

/Patrick

>===== Original Message From Todd Last <Rubatoguy@MINDSPRING.COM> =====
>Here is what I was told.
>
>If you have any leaks, and switch from dino oil to an all synthetic oil, your
>leaks will probably get worse.  This is because the dino oil causes the seals
to
>swell slightly - synthetic does not. So when you switch to synthetic, any
>swollen seals will shrink back to original size. Hence the often heard
comment
>that "I switched to synthetics and my motor started leaking."  This may or
may
>not happen to you - but high mileage engines seem to be most prone to it.
Oh,
>also synthetic oils may also pull some existing sludge back into suspension,
so
>if you have a leak that is plugged by a little sludge, switching to synthetic
>may cause a leak in this instance too.
>
>Todd
>'88 Westy
>
>
>
>John Rodgers wrote:
>
>> Somewhere along the way in life living with a Vanagon, I have read that
>> the synthetics may very well cause seal seapage, if you are switching
>> from Dino oil to synthetics. If you sart out with all new seals and all
>> new synthetics then it is not a problem. Never quite made sense to me,
>> however. But minor seepage doesn't hurt anything. Just be sure to do a
>> tranny level check at routine oil changes and you will always catch it
>> when the tranny oil begins to get low.
>>
>> John Rodgers
>> 88 GL driver
>>
>> Blake Thornton wrote:
>> >
>> > Well, I got around to putting in new transmission oil yesterday.  I
>> > drained the old (brownish in color) and cleaned off my drain plug (it had
>> > accumulated quite a collection of metal fragments).
>> >
>> > I then opened the bottles of redline MT90 and saw pink.  I was
immediately
>> > worried but then realized that redline is synthetic and not dino oil.  So
>> > I dumped it into my tranny (ok, I actually pumped it in with a fluid pump
>> > and it worked great).  I used about 4 quarts in the tranny and about 1/5
>> > of a quart on the ground (oops!).
>> >
>> > I then drove around after buttoning everything back up.  My van shifted
so
>> > wonderfully!  I couldn't believe I was driving the same van.  I wish I
had
>> > done this earlier.
>> >
>> > Just thought I'd post my success.
>> >
>> > blake
>> > 84 westy
>> > SLC UT