Has anybody tried using Z-max or other additives to there engine, fuel and transmission?

If yes, did they see any difference in there car(the way it runs) and if anybody tried any other types could you please share your thoughts on that?

Thanks in advance.

 

I've heard many bad things about Z-max, much of it involving federal investigations and lawsuits. I'd steer clear of their products.

 

the FTC investigation didn't prove it was "snake oil". I tried it in my truck ('99 5.3 Chevy) and it did absolutely nothing. So I sent in the little card to get my refund. I wouldn't use the stuff on "real" car.