It's an O ring, but when the thermostat gets deformed and mangled by
overheating once or twice, it will be burnt and will leak or drip.
You can put anything you like there, as long as it seals well.  I put some
Right Stuff with the O ring.  High heat will kill any of it.
Zoltan

----- Original Message -----
From: "azsun99" <azsun99@EARTHLINK.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, April 07, 2009 6:03 PM
Subject: seal at lower t-stat housing to cyl head

> This is on a '90. The ETKA calls it a seal and when I removed the old one
> (it was
> leaking), it was a flat seal, not an old hardened o-ring. When I asked for
> the seal at
> a VW dealer in San Diego, they gave me an o-ring. It does not appear to be
> anything
> special, but I am concerned with the high heat in that area.
> Has the flat seal been superseded by the o-ring?
> Thanks,
> Jerry in AZ