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Hello all first post and just a simple one, what do you all reckon the best fuel treatment is for the 4.2 s4 engine that's readily available? Done quite a bit to the car since buying and this is next on the list just for a wee bit of tlc for the engine!

Firstly FON. As far as I'm aware you don't really need fuel additives in these. Most fuels have them added already. Better just to make sure it is serviced regularly and keep a regular check on the oil level. They do like to drink a drop or two.

Ok thanks for the info on that batfinnk I'll not bother then, just bought the car in November there and got it a full service and health check pretty much straight away, look after the car and it'll look after you eh!

Cheers for the FON by the way lo just clicked on it to see what it was!! Lol

Yep pretty much plus this is THE best place in the world for any information regarding the four rings. I would listen to advice on here over advice from Audi any day of the week.

Yeah defo it's just had a new dmf and clutch on Monday there after looking thru this forum r.e. the vibrations I was getting, car runs like a dream now for a high miler.

Cool. Where abouts roughly are you? If your in this neck of the woods there is a kent meet on the 3rd of Feb. there is a topic about it somwhere on here.

Love to but I'm all the way up in sunny Scotland (glasgow)

There's stuff you can get from audi called G17. It's a fuel additive.
I think it was supposed to be part of the service schedule, but no one does it.
It should defo' be used if there is a value difference between the values in block 32 ( fuel trims) between banks.

I used it recently and it made a big difference. The fuel trims were something like 1.8% bank 1 and 0.5% bank 2 before the treatment and spot on after it.


Regards, Chris.

Here's an extract from the Audi Workshop Manual:

G17 additive: adding
t When adding G17 additive into the tank, the ratio must be 10 ml of additive per 10 litres of petrol.
t The following table lists the quantities to be added depending on the fuel level indicated on fuel gauge.
Mixture ratio:

Indicated on fuel gauge G17 fuel additive
approx. 1/4 approx. 15 ml
approx. 1/2 approx. 30 ml
approx. 3/4 approx. 45 ml
approx. 1/1 approx. 60 ml


– Carry out the following steps, one after the other.

t Connect -VAS 5051/5052-
t Self-diagnosis
t Engine electronics
t Measured value blocks
t Select measured value block 32
t Display zones 2 and 4 (V6 and V8 engines)
Note: Add four times as much G17 additive if there is a deviation of > 15% in the values.
WARNING
If the values deviate by more than 15 % repeatedly, a repair measure must be performed.