Based off of what, the aeroquip stamp is different for aircraft grade vs all the normal stuff. There is no “an grade” unless your speaking of mil-spec, but no civilain aircraft is needed to use mil-spec anything. I am allowed to use (under 14 cfr part 43 ) to supply my own parts as an owner that meet the original design criteria. For all small aircraft with working pressures under 3,000 psi, anything will pretty much work. How do i know, cause the FAA licensed me to know. The ferry stuff is just as good as anything else you can buy. I would think that car has nothing over 3,000 psi, so your fine.