This is the best and only oil for your Datsun 5-Speed. It will take a bit less than 2 quarts. This item is sold by the quart. This synthetic base oil has a very high viscosity index which provides relatively constant viscosity as temperature changes. MTL is a low 75W, almost a 70W, at very low temperatures and a high 80W, nearly an 85W, at elevated temperatures, providing adequate viscosity to prevent wear and deaden gear noise.