If you use the START/STOP function frequently you will need to perform engine oil changes at regular intervals 10 000 miles, if not you can extend that to 20 000 miles, or even 30 000 miles. IMPORTANT: first service needs to be performed at 10k miles/1year due to the process of piston rings settling in and sending tiny metal parts into your oil/filter. After that you can extend the intervals.
Transmission officialy doesn't require a service (so-called sealed for life unit), but the previous 6-speed wet clutch required a service at 40k miles, so i recomend you should change the oil/filter at about 70k miles, because those DSG units are oil-quality sensitive and expensive to replace.
If you went with the 4x4 option, than the Haldex unit needs a oil change every 3 years (no filter here), though you can extend that if you have low milage and you don't do much off-roading/driving on wet roads on hilly terrain.
The timing belt is another lifetime part, so shouldn't require replacement until 200k miles.
You have your fuel filter that needs replacing at about 70k miles, along with the engine air filter. On petrol engine you have spark plugs that last 70k miles and ignition coils that last about 100-150k miles.
Engine oils degrade if:
- exposed to high temperature
- exposed to contamination
- mechanical stress
- time
Due to modern day advances in mechanics, engines, transmissions and differentials work at higher tolerances and require very clean oil (cleaner than in older cars). Expensive synthetic oils last longer than mineral ones, but have different properties (VW wet clutch DSG problem/fix). Don't try and skip service intervals because, this can lead to expensive mechanical fixes down the road and it will void your warranty.
Where you can save on:
- spark plug replacement
- ignition coil replacement
- pollen filter
- engine air intake filter
- fuel filter
- performing oil changes yourself