i use synthetic in my late brother's colt, which has 214,000 miles on the clock. he fed it a steady religious diet of castrol conventional, every 2500 miles, for a total of 100 oil changes, which cost a total of about 1600 dollars. right now, i run in it 50:50 synthetic (group 3), and the modern conventional (group2). the vehicle runs like a dream.
this is the 1.5l mitsubishi mirage/colt.