im currently using 10w30 in my 4.6 f150 truck.with the winter months coming im going to switch to 5w20 will it be safe or should i go for 5w30 before going strait to 5w20.im not in to the 5w20 yet i think its to thin but since ford calls fot that grade i guess i will try-it. but how about using 5w20 and adding a bottle of valvoline synpower oil treatment to it just to beef-it up?will it take the 5w20 out of range(grade)or will it be safe .that additive seems to have lots of moly and boron wich i understang are really important specially in that thin oil. anyways thanks. any comments please?...........

 

I'm curious, if you are worried about what oil Ford calls for why are you using 10w-30?

Going from 10w-30 to 5w-20 is no problem.

Most oil addatives are snake oil and not needed. Some can void your warranty.