I don't think you can directly compare Turbo plug heat range to regular plugs. No you can't convert a 1/4-32 head to turbo. I buy Klotz from them at Toledo. I picked up three quarts for $14 last year. I have also used Maxima Castor 927. It has an additive to reduce carbon. I'd love to try FHS oils but they have no specifications and an email didn't turn any up. I'm going to try calling them.