MOGAS with ethanol and Permatex Aviation Form A Gasket

Thank you all for your answers.

The reason for this thread is that a few days ago, in a pre-flight inspection, I noticed a stain under the electric pump. The stain came from the 1/8" NPT fitting on the side of the fuel tank (low pressure) that I sealed 2 years ago with the Permatex Aviation, so this connection has been working well all that time.

Looking at the product's technical sheet you can read: "The product retains effective properties in contact with water, ethylene glycol, gasoline, motor oil, transmission fluid and sea water." That is, it doesn't mention ethanol and mentions gasoline, but ... ¿aviation gasoline?. It does not expressly cite MOGAS with ethanol.

It can also read: “For Cleanup 1. The product can be removed from metal surfaces with isopropyl alcohol. If the sealant has been dried for a long time or at high temperatures, cover the sealant with alcohol and allow to soften overnight.” In other words, alcohols seem to dissolve the product.

All this leads me to suspect that Permatex Aviation FormAGasket #3 is not suitable for pipes conducting automotive gasoline with ethanol, which is mandatory use in Europe.

Of course, I have removed all previously sealed gasoline fittings with this product using Loctite anaerobic sealing based on methacrylate that does resist ethanol.

I use Hylomar Blue. It's made for many fluids. Flight Design aircraft company uses it too. I've never had a leak from using it. I use it on gaskets and threads for fuel and with ethanol. 

https://hylomar.com/en/universal-blue/

https://www.amazon.com/Hylomar-Universal-Non-Setting-Silicone-Jointing/dp/B07NJHZJQQ

Thank you very much Roger.
Thanks to your feedback, I now know which sealing products work and are safe in the long run.

The main reason for this thread is to warn that a product advertised and recognized as suitable for sealing aviation gasoline connections may not be reliable and safe when used with ethanol automotive gasoline (MOGAS).

Saludos.

Thanks Roger. Hylomar is now in my Amazon shopping cart.  I’ve had little to no success with Permatex FormaGasket products and I only use ethanol-free Mogas.  Most of my fuel connections eventually ooze brown gooey stain and I’ve even had fresh from a new can permatex fail to set to the tacky consistency necessary for assembly after three days sitting on the bench applied on a clean aluminum npt fitting. I can’t figure out why it’s so popular.

Jim Isaacs wrote:

Thanks Roger. Hylomar is now in my Amazon shopping cart.  I’ve had little to no success with Permatex FormaGasket products and I only use ethanol-free Mogas.  Most of my fuel connections eventually ooze brown gooey stain and I’ve even had fresh from a new can permatex fail to set to the tacky consistency necessary for assembly after three days sitting on the bench applied on a clean aluminum npt fitting. I can’t figure out why it’s so popular.

Hi Jim,

The Hylomar Blue works well just don't  over apply it. It doesn't take much.