What type of oil do you use for a 1986 ford f-250 diesel?
1986 Ford F-250 diesel requires a 15W-40 oil. The 15W-40 specification applies to multigrade oils commonly used in automotive applications. The first part, the 15W, indicates the oil meets SAE (Society of Automotive Engineers) standards to flow and provide enough lubrication at low temperatures, up to -13 degrees Celsius (8.6 degrees Fahrenheit). The second part of the specification, the 40, denotes the oil retains acceptable viscosity when tested at 100 degrees Celsius (212 degrees Fahrenheit).