Originally Posted by swerver

I buy Castrol GTX 5W-20..........manual doesn't recommend synthetics and I treat the manual like the bible.................

Originally Posted by Rotary78

this has been debated for a while now within the members... Mazda North America says not to use synthetic oil due to the fact that its very thin oil, which means potencially the oil won't last long becuase the rotary engine will eat that up, but there really hasn't been any proof of it, but Mazda just wants you to be safe.... Bottom line use what you want!Heres some you can use:

Mazda Certified from the dealer 5w-20 (Non Synthetic)
Castrol GTX 5w-20 (Non Synthetic)
Valvoline 5w-20 (Non Synthetic)
Pennzoil 5w-20 (Non Synthetic)
Royal Purple 5w-20 (Full Synthetic)
Mobil 1 5w-20 (Full Synthetic)