Comparative Study on Transportation Efficiency and Cost of Trucks Using Ck-4 And Ci-4 Engine Oils in A B C Stone Mill Co., Ltd., Saraburi Province

Abstract

         This study aimed to (1) compare fuel consumption rates of trucks using API CK-4 and CI-4 engine oils, (2) compare total transportation costs between the two engine oil standards, and (3) examine the correlation between Total Base Number (TBN) of engine oil and fuel consumption rate. A crossover field experiment design was employed. The sample consisted of 10 heavy-duty trucks from a stone mill company in Saraburi Province, divided into two groups of five. Data were collected from 500 actual trips over a two-month period (one month per oil type per group). Research instruments included a GPS vehicle-tracking system, calibrated fuel consumption measurement devices, and engine oil property analysis conducted by an ISO/IEC 17025-accredited laboratory. Data were analyzed using paired samples t-test with the individual truck as the unit of analysis (n = 10), whereby per-truck averages were computed prior to comparison after 10,000 kilometers of use. Results indicated that (1) trucks using CK-4 engine oil had a significantly lower fuel consumption rate than those using CI-4 engine oil (t(9) = -3.21, p = .011, Cohen's d = 1.02), (2) trucks using CK-4 engine oil had a significantly lower total transportation cost per trip than those using CI-4 engine oil (t(9) = -3.856, p = .004, Cohen's d = 1.22), and (3) TBN of engine oil after use was negatively correlated with fuel consumption rate (r = -.74,
p = .014), representing an associational rather than a causal relationship. The findings demonstrate that API CK-4 engine oil has the potential to reduce fuel consumption and transportation costs under real operational conditions in the stone milling industry. However, the findings are limited by sample size and duration of the experiment and should be applied to other contexts with caution.