[findalex]

I've never seen anyone using the cleaner straight with a gasoline engine car, and there's probably a ratio of cleaner/gasoline that works best. It's the same principle as buying concentrated dish soap and just using that to wash the dishes. It would be too thick and harder to clean the dishes. You need the soap to dissolve/bind with the gunk and water to carry away the upper layer of gunk before the soap can dissolve/bind with the next layer of gunk underneath.

From what I have gathered, most cleaners use the same chemical as Chervron's Techron with various degrees of concentration. Techron is cheap at Walmart, so why not just buy a bunch when it's on sale and dump it into the tank? I just buy them when the local auto parts store have 2-for-1 sales and use 1 bottle per fill up, 2 fill ups in a row.

With too much cleaner you will have less effectiveness so you're basically just wasting money in my opinion. If there is evidence to the contrary, I would love to see it.

 

[findalex]

BG 44K also has good reviews. I used it once on my A5 2.0 TFSI and A3 2.0 TSI and had good results.

However, it's much more expensive than techron so I switched over to techron recently.

BG 44K is $23 for 20 gallon treatment = $1.15 /gal
Techron with Autozone BOGO is $9 for 24 gal treatment = $0.38 / gal

I've just finished running through 2 bottles ($9) worth of techron and the car's slight shaking while cold idling has disappeared just like when I used BG 44K.

 

[findalex]

Did you follow the manufacturer's concentration?

Assuming you're using the Pro-Tec Fuel Line Cleaner, the mixing ratio is 1:200. So 25 liters of fuel only requires 125 mL of cleaner. If you put too much, then you won't get the optimal cleaning result.

More is not always better. If it is, the manufacturer will make much more money if they just tell you to use the mixture at 100% cleaner / 0% gasoline.