and in pre-catalytic converter cars (or gutted cats) that's fine.

 

i can't ever remember seeing a single independent test
of either Royal Purple or Amsoil
in the last 30 years

i know of not one
18 wheel trucking company
with more than 30 trucks in the fleet
that uses Royal Purple or Amsoil

neither Royal Purple or Amsoil
has done a SAE/TMC fuel economy test
to back up advertised claims
but instead use the trickery of
"Customers report that.... "

Keep in mind that a company could truthfully say that
"Customers report that Elvis is alive and living in their basements"

that is not saying that either company
does not have a better than average oil