The paper is trying to give information about motor lubricant oil its grades according to relatively international standard. The paper suggested that due to poor oil personnel experience in Sudan lubricant oil choosing and change shows less effectiveness. The objectives of this study are to give the condition of maintaining correct time for the motor oil changing and the suitable oil type that helps to optimize lubricant cost and performance for motor engine. For that the process of fixing motor oil type and changing duration is done by using a mathematical model that has a direct relation to economical concepts and machine technical condition. The study used a data of an experimental work done by Honda International Company for an engine oil to fix its duration interval. Also the paper shows that the machine lubricant industry specifications, its general grades and machine manufacturer directions are very confusable. They are in a constant state of change; therefore the printed information’s may not reflect the latest specifications. So from the side of motor oil users and engine manufacturer they are asked to update continuously their information. The paper is suggested that an international effort should be done extremely in the field of lubricant oil quality control and to give lubricant oil personnel considerable training to insure suitable oil and safety timing for machine oil changing. No doubt this leads to lengthen machine time life duration, helps to lessen machine wearing, car failure, environmental risk and to minimize maintenance cost. Paper is suggested that all new car engines should be provided with the oil life monitoring systems that notify the driver when an oil change is required.