The 1983 Castrol 400 was an endurance race for Group C Touring Cars held at the Sandown Park circuit in Victoria, Australia on 11 September 1983. The race was staged over 129 laps of the 3.1 km circuit, totalling 399.9 km. It was Round 3 of the 1983 Australian Endurance Championship and Round 3 of the 1983 Australian Endurance Championship of Makes. The race, which was the 18th annual Sandown long distance race, was won by Allan Moffat driving a Mazda RX-7.