A4 Avant TDi Oil Cooler replacement advice

[Dune]

Hi folks,

I've just bought an A4 Avant TDi 1998 and would like some advice on how to change the oil cooler - I have oil in the coolant. The Haynes manual hardly gives it a mention yet it seems to be a common problem.

Also have some other other queries:- high pitched whistling noise which rises in pitch with the engine, creaking noise from RHS front wheel/suspension when coming off a bump, and slightly vague steering when in the central position. Lastly the previous owner mentioned that the red i on the badge is significant. Can anyone tell me why?

Oh two other things - how do I find out what the engine code is and should there be an outside temperature display - the user manual shows it but that part of the dash is blank.

Thanks