I don't have a cite, but I know I read somewhere that you are not supposed to use synthetic oil in the RX8 because the oil is used to lubricate the rotor seals. Something about the synthetics having a different flash point... I'm no expert, just passing on another theory.
Also, I'm fairly certain the Mustang's replacement will be an 8 as long as it works as a 4-door family car :)
