I had a '93 Taurus SHO with the Yamaha v-6 that used regular Pennzoil and it started using
oil at about 80,000 miles. Later I had a '99 Taurus SHO with the Yahama v-8 and used
synthetic and it never used a drop of
oil up to when I sold it at 143,000 miles. I've also been told by a friend whose career has been in the
oil industry that there are only 3 oils that are truly
synthetic--Mobil,
Amsoil and Redline. All others are supposed to be derivatives of pertroleum products. Also have a '04 Viper (78,000 miles) as well as a Hyundai Azera (93,000 miles) both of which have always had
synthetic and never used a drop of oil.
They've made a believer out of me