I have a new Mazda rx-8 rotary just about due for its first oil change. It is not my first rotary (I've had 2 other rotary cars and 1 motorcycle) There is a real debate about synthetic oil useage in rotaries with a lot of strong opinions on both sides. I have used Amsoil for decades in my nonrotary vehicles and personally believe it is the best oil available. I never used it in my rotaries due to financial (oil use) issues. The owner's manual stipulates 5w20 oil. There does not seem to be an abundance of choices. I have decided on motorcraft 5w20 - a product with Ford's name on it (a part owner of Mazda). The oil is supposed to be a blend of synthetic and dino oils. Does anyone think that would be an issue with this engine?