My best friend is getting his dad's 1989 Mitsubishi Mighty Max Pickup truck and wants me to do some things to it before he starts driving it. First off, it has 180K miles, its carberated, no power steering. His dad almost ruined that engine by using STP 4-cyl oil treatment. The mechanic somehow fixed it but its not like it was before. He doesn't like the lengthy procedure of Auto-RX because he won't be driving that far very easily and he doesn't wanna hassle me. Is 1 quart of ATF with a new filter, running for say 1 hour at idle enough to safely flush the engine? I ran a motor flush in my 4.0 Jeep with no problem but his mom is paranoid about it.