Oil, Redline Synthetic, D4 ATF

As with all of their fluids, Redline ATF is the best. D4+ is the appropriate choice for all years of Miatas (but not the Fiat 124). Excellent for high and low mileage transmissions, with balanced slipperiness for easier shifting in cold temperatures. Compatible with petroleums and other synthetics. 

Four quarts required for all automatic Miata transmissions. Well, not if you add them all together. But you know, each one on its own.