BSilveira,
If you are noticing an increase in performance and/or fuel economy with a fuel additive that incorporates cetane boost then it may be beneficial for you. You have to decide if the added cost of the additive offsets the lack of economy and/or power.
I have two friends, here in Phoenix, using Stanadyne Performance Formula & I have been using Promrose Power Master 405. None of us have noticed an appreciable power and/or economy increase.
Basically, that means the fuel we are buying has enough cetane in it,already. Your engine can only use so much cetane. The rest is a waste.
BTW, most of the fuel we get here is from CA.
I, almost always, buy Flying J fuel because of it's price. Seems to be a quality fuel. Been using it for years. My buddies use whatever is available & convenient, for them.
If you are not noticing a power and/or economy increase, then an additive with lots of lubricity might be something to consider. Stanadyne has a "Lubricity Formula" that has 3-5 times the lubricity of their other Formula's & it's much cheaper. I'm most concerned about the low lubricity of modern day fuels.
I do not know anything about the Amsoil product, you mentioned.
Hope this helps.
Joe F. (Buffalo)