IT WORKS!(I still don't believe it.)
Here are stats Hyundai Elantra XD 1.6 300.000km driven.made a piston soak with a B12 cleaner..AFTER that piston knock on idle started.also piston slap....I was ready to dismantle the engine to change rings and-or pistons. ...So I found XADO..as a car mechanic I don't trust "snake oils" BUT that think after 1500 km made my engine sounds as new!!!NO MORE noises or slight vibration.i have drive 4500km after it.also oil consumption drops to 100ml for 1000km.pretty impressed!!!
