Seized brakes?

[Panteracer]

My Pantera had the front brakes lock up two years back
Installed a new Master then and good until Monterey weekend last month
and the same thing happened.. Ordered a new AC Delco master
but still made in China... decided to take the old and new to
Power Brake Exchange in San Jose and have them figure out what
is the issue

Seals were swelling up so it would not return.. so he asks me what type of Brake fluid I am using... Was running Castrol dot 4 lma until about 6 years back when I Switched to Motul 600 motorcycle fluid for the high heat
My Viper buddy was running it in his car so decided to change
I guess it is what has caused the swelling. Had power brake exchange change out the seals in both the new and old master to a Raybestos usa made seal that he gets out of Texas

Hopefully my brake issues every two years will go away

Bob