What is this line listed with oil change?

[SeeDanPaint]

I need some help to identity this line on an invoice from my last oil change, the dealership permanently closed so I can't ask them. Any idea on what this is on a line listed with oil change, "95 AVW - Diesel Con"? I thought this might be AdBlue, but I understand that my 2013 Golf TDI doesn't have a DEF system...

I can't find any reference to this anywhere, just trying to figure it out so I am not missing anything at my next oil change.
Thanks.

 

[oilhammer]

Diesel Fuel Conditioner, an additive put in the tank, would be my best guess.

 

[SeeDanPaint]

Diesel Fuel Conditioner, an additive put in the tank, would be my best guess.

So like STP? I'm guessing this isn't totally necessary. I'm sure I can find a few threads on fuel conditioners, some people swear by them.
Thanks for the quick reply!