For years, TxDOT used re-refined conventional oil for its pickup and dump truck fleet. Though conventional oil is cheaper to purchase, it requires more frequent oil changes, thus a relatively higher Total Cost of Ownership.
Though synthetic oil is three times more expensive than re-refined conventional oil, it lasts five times longer, which reduces the amount of labor required to perform oil changes and results in a lower Total Cost of Ownership.
Switching from re-refined conventional oil to synthetic oil in pickup and dump trucks will save TxDOT $1.4 million annually. The conversion to synthetic oil was implemented department-wide in March 2013.