well ive been using mobile 1 syn in everything,for about 18 months.the main hoped for result was cooler running. this is my impression . in small engines it lubricates no better than good spec dino. with proper changing i dont see it exstending life of the motor. this from someone who has always been able to get very good hrs out of any motor. i dont think its going to give me the exstension on my command engine ,that i was hoping for,for the exstra cost. i recently had my wifes escort start a little oil trickle back, after it was left setting over nite. changed to dino. and after 2 days no more smoke in the mornings. my mechanic says he thinks syn may harden the valve stems .my experience would verify that, imho.i added a seal softner ,but was very surprised when the motor quit smoking in the morning. any with a long hrs motor, may have seen the same thing.this post is not to state absolutes ,only to give my observations . perhaps this may help someone.