What advantages if any would there be to switching to mobil 1 full syn. 5w30 after using the same brand 10w30? Can i switch to 5w20 or even 0w20 full syn. without any kind of engine problems in the future? I've got a 97 f150 with the 4.6 and have 102k and have been using 10w30 mobil 1 for about 2 years now.