Did you test the two oils in the same conditions? What was the ambient temperature at both tests? What was the temperature of the two syn oils compared to a conventional oil? What driving did you do while testing?
I did an experiment with my 91 civic right before I got my celi. I had an oil temp. gauge and I used MOBIL full syntetic and I also tried CASTROL syntec. The temp. on the CASTROL SYNTEC was lower than MOBIL full syntetic. After that I use only CASTROL SYNTEC.