Ha ha – balls!
This claims to increase the octane of unleaded fuel to that of the old 4-star leaded stuff. Maybe it does, maybe not. I’d imagine not. But that’s not the problem that unleaded petrol can cause for us. This thing will not replace any lead that is required to cushion the valve seats.
I run an additive from time to time – mainly when I expect to be on the motorway – to help avoid this problem. I don’t bother when just pootling around.
Conclusion – would not use.
Chris