The Factory Seals are Buna-Nitrile and don’t hold up.
Viton is the way to go. Viton has superior chemical
and temperature resistance over Buna.
A Note About Viton - We only sell Brown Viton O-Rings.
This way you know what you are getting. With Black o-rings,
Your guess is as good as ours. We have found some people
Sell Black Buna o-rings and are calling them Viton.
Make sure you get Brown Viton!