What about compression, will it increase after brake in?tnmemr said:No synthetic.
Synthetic does not let the rings seat very easily, and you will have more blow by. BTW: Your XLT does not have nikasil cylinders. You may know this, but 1 post mentioned nikasil and it does not apply in this application. Letting the motor go through the 2-3 heat cycles by allowing it to idle and/or light revving and totally cool reduces the worries of breaking it in too hard.