[Ihadathoughtonce]

Hi not long bought this A5 3.0 TDI seemed mint when I bought it and I remember doing coolant check where I could smell no oily smell no oil on the surface and the reservoir looked clean and after a run didn't move. So had it now for about 5 months suddenly in the sunlight I see what looks like mud in the coolant bottle it's level has dropped and it got rusty residue on the sides
No mayo in the reservoir and no mayo on the oil cap .
so am I right to assume this could be down to someone previous mixing coolants not using g12 or using water
And it's just rusted the radiator inards
Anyone has this before and had a successful flush I'm not sure what's best on these beasts first time with a v6

 

[SimonRoma]

Ello mate welcome on board!!! I would not let this worry toooooo much cos you have caught it early. By all means flush the system and then refill with the correct coolant mix using only VW/Audi approved fluids. My old S4 recently needed a new rad cos the old one rotted from the inside!!!! Must have had wrong fluids for years I guess.