Methodology for the calculation of consumption of the lubricant oil in internal combustion engines of offshore vessels

The consumption of lubricating oil in diesel engines of offshore vessels has gained prominence, becoming essential for cost control and reliability related to engine lubrication. The lubricating oil used has an average price of US$ 2.35/l. Therefore, 5,000 liters of this oil cost, on average, 11,750 dollars. A certain company that has a fleet of three drilling ships that uses this lubricant will have a considerable cost with the oil, because, on average, if you consider that each ship consumes 10,000 liters per month, this gives an expense of 23,500 dollars per ship and, consequently, a total expense of $70,500 per month. When failures are found in the lubrication system (due to oil deficiency or excess) of a mechanical set, among poorly lubricated parts, some with serious damage caused by overheating due to dry friction are found. Too much lubricant also causes damage to engine parts and components due to sliding friction. The reality of companies is portrayed by imprecision regarding the consumption of lubricating oil. In this sense, the work in question deals with the implementation of improvements in the consumption of lubricant in diesel engines in order to solve the imprecision of the amount of oil effectively consumed by diesel engines, using the methodology of probability distribution t student derived from the statistical inference which provides an estimate of lubricant consumption through the confidence interval containing the true average of all lubricating oil consumptions of engines with 95% confidence. The data were collected in the form of samples and were treated using information on specific consumption of lubricating oil through the g/kwh ratio provided by the diesel engine manufacturer's manual. The proposed methodology presented a good degree of precision, because for the period of operation of 10 days of the engine, the average value of oil consumption was established by the confidence interval of 16.86 liters to 21.01 liters per day. When using the current method, only the average value of 26.75 liters of oil consumed per day was obtained. When comparing the two methods, it was found that the proposed methodology is superior to the current method.