Ok...this is only for petrol engines !!!
A lot of fuel system cleaners use up to 80% Kerosene with the rest being made up of solvents such as xylene and a few others.
The ratio is pretty much reversed with "instant" cleaners which are about 80% solvent and 20% kerosene.
Kerosene in the UK is commonly known as paraffin.
So..............you see where I'm going ?
A 300mL bottle of fuel additive is about £6. You can get a gallon of paraffin from a hardware store for that.
So every 3000 miles I lobbed in 300mL of paraffin. Lots of the guys on the 155 forum did this and noticed the improvements in car power and also the general running, as you would expect after running fuel system cleaner for the 1st time.
2 things....as I say, this is for petrol
engines only and it also has to be proper paraffin
and not the new eco-synthetic stuff. Problem is proper paraffin is getting harder to find, but fear not.......you can use 300mL of diesel instead
I now drive a diesel and believe that petrol can be used as a cleaner, but I haven't looked into it yet.