Totally a subjective opinion about the two main oils being
discussed...the Redline and the Swepco.  Simply my own observations, having
run both oils, back to back, several times in a couple of vehicles.. the
choice often dictated by expense and availability issues.  I have never
found Swepco available in any stores, though one racer supply shop near
Portland Int. Raceway had it on the shelves.  It's also more expensive than
Redline by quite a lot, especially when  required in large quantities.

  I've used both of them in more than one German vehicle.   There are some
very noticeable differences in the way the transmissions shift and the
'feel' coming  into the chassis from the gears as you run down the road.
On one of my vehicles, which had a gearbox oil temperature gauge, the
Swepco consistently ran at significantly cooler temps under the same
loads...by about 25 degrees F.  My personal Internet guess as to why this
was is that the Swepco is a better lubricator and hence lets the gears turn
with less friction, creating less heat.

  My transmission guy showed me a 'test' once where he dipped a bladed
screwdriver in Swepco and handed it to me, blade-up and said..."Grab the
blade with two fingers and hold it upside down"....I could not squeeze it
without the blade squirting out and the screwdriver hitting the bench....He
wiped off the driver and dipped it in some Redline gear oil, then handed it
back to me, same way.  I had no problem taking it upside down and holding
it with the handle dangling....   So, with a scientific test like that,
plus the sounds my ears hear and the 25 degrees cooler temps after a 20
minute racetrack session, I've decided to use the Swepco when I have a
choice.

  There is a significant difference in how the NS Redline oil behaves.   I
used a specific blend, a ratio dictated by my transmission guy, to get the
differential performance I wanted from the much modified limited slip
(clutches) in my old race car.  The Swepco seemed to work well right out of
the bottles.   Not germane to Vanagons, the blending of NS and normal
Redline, other than to note that it certainly is a different formulation.

   In my humble opinion, the Redline oils are too thin.   They make the
gearbox noisy and in my one vehicle with a tranny temp gauge, they allowed
hotter running temps, all else being the same.    Redline does shift easier
on cold start up.  Swepco is a bit 'stiff' when cold, and if I drove often
in sub-freezing, I would probably use Redline during the winters..

  So, totally unscientific observations.  Oh yes..... I know many many of
the experienced racers and builders of racecar gears swear by
Swepco...Daryll says it's good, too.   When I have to decide how to do
something, but I don't have the time or inclination to delve into all the
science and to research things endlessly, I usually look around at what
other successful people, doing the same thing, are using...I ask around,
too....and then I just do the same thing...Works for me.

  Don Hanson