What's
Hylomar? It's a sealant that is non-hardening, and it's impervious to gas and oil and also high temperatures. It's very well suited for helping seal your valve covers.
Ratwell recommends it and I believe Jake Raby does too.
For years, it was available as Permatex #25249 and available at any auto parts chain. At some point, the company that supplied Hylomar to Permatex decided they wanted to distribute it world-wide, and they raised the wholesale price up 10x. As a result, Permatex stopped carrying it and didn't have any suitable replacement. It became very hard to find in the US, and even harder to import, at least in quantities suitable for the average VW owner.
I happened to check the other day and noticed Advance Auto Parts listed Hylomar as Permatex #85249. It's the same stuff so at some point they must have resolved their distribution issues and brought it back on the market. It's about $11 for a little tube but that should go a long way.
I tried some on my valve cover gaskets because I couldn't get them to stop leaking. I got two brand new cork gaskets and cleaned the sealing surface of my valve covers really good. Then I applied a thin film of Hylomar and placed my gasket in. Along with the gel, there is a solvent mixed in that evaporates almost immediately when you squeeze it out, so it's ready to install right away. I left the head side of the gasket dry. Reinstalled my valve covers and they have been dry ever since. I laid down some paper towels overnight so I could see right away if there were any leaks.
So there you go, Hylomar. It's a blue gel and reminds me a little of runny toothpaste. If you'd like to borrow some the next time you replace your valve cover gaskets, let me know and I'll loan you mine.
