See Figure 1
All Jeep engines prior to 1975 are designed to operate on regular grade gasoline. All gasoline engines, 1975 and later, are designed to run on unleaded gasoline.
Many factors help to determine the proper oil for your Jeep. The big question is what viscosity to use and when. The whole question of viscosity revolves around the lowest anticipated ambient temperature to be encountered before your next oil change. The recommended viscosity ratings for temperatures ranging from below 0ºF to above 32ºF are listed in the accompanying chart. They are broken down into multiviscosities and single viscosities. Multiviscosity oils are recommended because of their wider range of acceptable temperatures and driving conditions.
The SAE grade number indicates the viscosity of the engine oil, or its ability to lubricate under a given temperature. The lower the SAE grade number, the lighter the oil; the lower the viscosity, the easier it is to crank the engine in cold weather.
The American Petroleum Institute (API) designation indicates the classification of engine oil for use under given operating conditions. On gasoline engines only oils designated for Service SE/SF, or just SF, should be used. This oil provide maximum engine protection. Both the SAE grade number and the API designation can be found on the top of a can of oil.
Non-detergent or straight mineral oils should not be used. Oil viscosities should be chosen from those oils recommended for the lowest anticipated temperatures during the oil change interval.