Fits 1986-2011 All RX-7 and RX-8 Engines but doesn't work for rotary engines before 1986. The factory thermal pellet acts like a thermostat for the oil system. When the oil is cold it does not allow full flow to the rotors for cooling, only enough for the bearings. As the oil warms up it allows more oil to flow. When this fails, it does so in the cold mode, thus not allowing oil to fully flow to the rotors, which overheats them and causes damage to the oil control rings. This does not increase oil pressure. Our replacement pellet keeps the engine oil in warm mode so that oil is always flowing to the shaft thus fixing the problem of the faulty factory thermal pellet.