Answer: Long enough before it breaks and destroys your engine, so you can sleep at night. Audi recommended "90K miles" .... but they backed off on that figure when belts started breaking @ 60K miles. For a good night's rest, check the belt for signs of wear or checking @ 40K miles. If it's still like new, then replace it @ 60K miles .... IMHO. This is one area where an once of prevention is worth a ton of money.
Audi recommends every 75,000 miles.
No such thing. The Audi's thermostat has a wax impeller.
The clue is in the numbers. 18t is an 1800cc turbo, the 3.0 is a 3000cc engine.
The Vehicle does not have a blow off valve. so you will never find it.
5t-26 = 18t -26 = 18t -5t -26 = 13t t = -2
18t + 4x -47t + 50x = -29t + 54x
They're the same.
You need to put some heat in your gas tank; sounds like you have water passing through the fuel injecters dirt in the intake manifold/throttle/air flow meter
3(5 + 6t)
6t
take it to a garage
(t - 7)(t - 11)
This is how I changed mine: You need a socket set and a screw driver. Open the boot and in line with the light there should be a round indent in the carpet. Flick it open with a screw driver or something flat. Now in the hole there should be a hexagonal bolt. Get the right size socket and start unscrewing until the whole casing comes off. There should be two plastic retaining clips which you can undo and change the bulb.