In API engine oil licensing, candidate oils must meet the performance requirements of category defined engine tests. While API category engine tests are developed to target a theoretical performance standard, it is rare that the cost to test and approve oils is understood.
Given that engine tests are an integral part of oil evaluation, understanding of engine test value is necessary. Therefore, measurements of value are presented as Unbiased Engine Test Evaluation (UETE). UETE evaluates an engine test's draw on time and money resources by estimating the average number of tests required before a candidate oil will pass the category defined engine tests. A pilot study using the API CH-4 Category is presented.