Gaskets and Hylomar

[KVH]

All the various kinds of Permatex have me confused. Low temp, high temp, petroleum, no petroleum, fast dry, 24 hour cure, gasket or no gasket, metal flange, sensor safe, and on and on.

Why not just Hylomar whether or not a gasket exists?

Can't I just use that right now on my water pump, with gaskets, start up and drive away and stop reading directions and comparing all the others?

 

[TR3driver]

Then I guess you'll really get confused when you see the Permatex Hylomar :laugh:

As I'm sure you've noticed, Permatex is a brand name now, used on all sorts of goop. But the "classic" Permatex is "#3 Aviation Form-A-Gasket" which is essentially modified gasket shellac. When I was a kid, that was what folks meant when they just said "Permatex". I still use it, but only in a few very specific applications (like the figure 8 gaskets and the felt packing for the rear main cap).

"Hylomar" is also a brand name now, and comes in at least 4 or 5 different formulas. My favorite is still the old "blue", but as near as I can tell it is illegal in the US (or at least in CA). Closest you can find is "Universal Blue Racing Formula", which I don't like as well, but is what I use on water pump gaskets and so on.

Here is a brief description of the various Hylomar formulas:
https://www.hylomarsealant.com/_resources/_html/products.html

 

[KVH]

Yes I should have clarified that my tube of Hylomar is also Permatex but it's the confusing bunch of other products and colors, etc. which at least for our cars seem largely unnecessary or inferior to Hylomar. I'm inclined to default to Hylomar every time.

 

[Geo Hahn]

I like Hylomar but do not use it all the time.

It seems to work best when you either have two machined or very flat surfaces meeting (typically with a paper gasket) such as the thermostat housing... or when there is a gasket with a lot of give like the valve cover cork gasket.

On my car at least I find the stamped metal parts (oil pan, timing cover, diff cover) do not seal well with just Hylomar and a thin gasket. For those I use something with more body on the part side of the connection and let the part-to-gasket half set up well on a flat surface (e.g. glass) so the result presents a very flat surface (the gasket) to the machined surface (block, diff, etc). On that latter connection I use the Hylomar for easy removal of the part.

Lately I have used 'copper' RTV for the part-to-gasket connection.

 

[KVH]

Thanks, Geo, I'll try that on my oil pan next time. I like the can of Permatex High Tack but it doesn't seem to seal that oil pan well enough. Assuming anything will...

 

[FordFiesta]

Coming from the background of using mainly Permatex #1 and #2, the existence of a gasket and thread sealer that's impervious to gasoline and other solvents is just flat-out amazing, and Hylomar blue has become my go-to sealant for all except exhaust manifolds and head gaskets.

Hylomar just makes everything else obsolete.....except for the heady smell of Permatex #1 warming up after you start up a new motor for the first time, which is pure time-travel if you grew up with the stuff.

 

[DougF]

I use hylomar on the transmission and overdrive, but use Permatex Right Stuff without gaskets (except head, manifold and oil pan) on the engine. It's similar to RTV, but imo much better. There is no set up time. A customer color tested it when used with gaskets, and found the gaskets to be weak spots.

I now use it with an oil pan gasket only because the seal was so strong when I removed the pan to install an oil separator fitting, I didn't want the struggles again should the pan some day have to come off.