Ive been using castrol active 2T now for about 2 months. Not sure on fuel economy because I don't really measure it as I'm lazy. But what I have noticed is when I start it in morning for work. It doesn't vibrate as much. Sounds more like a normal engine then an old tractor. Also found the power curve seems smoother. I was a sceptic at first but would recommend it now. I'm in a 1999 2.8 GU