I own a '96 Cobra with 110k miles. The engine is stock and non-aspirated. It needs new plugs. Is there any particular type/brand that will provide me the best performance (e.g., platinum)? Also, the radiator is a Fluidyne and the coolant needs replacement. Is there a preferable type/brand and should I add a corrosion/rust inhibitor (also type/brand?)? Thank you very much.