JMHO, but a 9.XXX compression engine should work fine with 87 octane. It is the other stuff that they add that will help or hurt the performance. I had a 74 Camaro that I drove as a daily driver around 2002 to 2006. It ran fine with the Chevron with Techron with 87 Octane. But if I went to any other fuel, it would ping if it wasn't the 91 octane.