BP Lubricants said it hired the independent laboratory Southwest Research Institute, in San Antonio, to analyze power output of gasoline engines with Royal Purple Oil and with BP’s Castrol oil for comparisons. “The results were provided to the challenger’s expert statistician who was not informed of the identity of the candidate oils,” *** stated. “The challenger’s [BP’s] expert determined a 0.9 percent difference in power between the oils, which did not rise to the level of statistical significance, and is well below the 3 percent claim made by the advertiser.”
SwRI did additional tests to independently determine the differences in fuel economy, emissions data and engine temperature between Royal Purple and Castrol motor oils. According to SwRI, “there was no statistically significant difference between the fuel economy, emissions data or engine temperature between the two candidate oils,” *** said.