Do Mazda RX-7 FD owners premix their fuel?

Yes, premixing fuel is a common practice for Mazda RX-7 FD vehicles, though whether it is necessary often comes down to your driving style and the modifications on the car. For a relatively stock FD, premixing is not strictly required as long as the factory Oil Metering Pump (OMP) is functioning correctly ¹.

If you are considering premixing your FD, here are the technical considerations:

• Emissions and Catalytic Converters: If you are running a functioning OMP, you should avoid premixing right before an emissions test. Furthermore, while premixing alongside an active OMP does not appear to negatively impact modern hi-flow catalytic converters, the long-term effects on a stock catalytic converter are uncertain ¹.
• Lubrication Quality: The factory OMP injects oil by dripping it into the engine. Premixing blends the oil directly with the fuel, allowing it to be sprayed as a fine mist through the fuel injectors, which provides highly effective and even lubrication for the internal seals ⁶.
• Refueling Routine: Premixing requires adding the oil at the pump during every fill-up. The simplest method is to prop open the flapper in the fuel filler neck, pour the required amount of 2-stroke oil in, and then pump your fuel so it mixes appropriately ⁶.

If you want the least amount of hassle with a relatively stock FD, keeping a healthy OMP, changing the oil every 2,000 miles, and taking the car to redline when warm to clean out carbon buildup are highly effective alternatives to premixing ¹.