My dad replaced the p/s line on my brothers 1991 Ranger. I know it calls for ATF so we have been using Type F to keep it topped off, but I noticed that he refilled the system with Napa P/S fluid. Will this damage the system in any way? I started it up for him and turned the wheel and it has the "normal" Ford p/s whine that it had before, it may be a bit quieter now that its full on fluid though. Just checking with the experts!