Premix is not optional on the FD,do it every fill

The 13B-REW's oil injection system is marginal from factory. Adding premix oil to every tank of fuel is the single best thing you can do for rotary longevity. I use Idemitsu Premix at 1:100 ratio, which works out to about 400ml per tank. Your fuel economy drops slightly and the exhaust smells a bit different, but the apex seals will thank you. Every long-running FD I know of runs premix. Every blown engine I've seen didn't.