This is a picture out of the ELF spec book.. this is an add WRITEN by Mazda and it specifically says.
"Super low viscosity engine oil based on the most advanced synthetic oil technology for mazda petrol and diesel engines. Reduces fuel consumtion by up to 6% in city driving (tested on a 4 cylinder engine) and maintains high level of engine performance. Its optimum protection againstr wear contributes to a long engine life. Highly recomended for use in Renesis engines of the RX8 sports cars."
If its good enough for Mazda to stamp their seal on it then it must be good enough to use.
synthetics have changed ALOT since the introduction of the rotary engines.
This talks about how the RX8 was recalled in ther begining due to faulty omp systems.
This one clearly shows what oil u need to use in the rotary (if the OMP is functional)
I use the 10w50 because I premix and dont use the omp.