Have 2007 Audi A8L. Living in Germany, want to

You may find one at a reasonable cost using google. Type into your serach box;
'Service manual for 2005 Audi A8L'

Skeeno,
Watch this YouTube video:
https://youtu.be/oiVs8Y466s8
Good luck.

Unfortunately, you cannot. Before replacement you needed to check gauge by grounding wire to block to see if gauge pegs, if the gauge does not move problem is in the gauge. I have worked on so many different vehicles, so my thought might be on a non digital type gauge not a digital. If digital gauge disregard this test.

Audi doesn't provide free owner manual downloads.

Look under the back seat !!

10000 km unless driving in dusty conditions then 5000 km

the diode maybe leaking or shorted out. It should only conduct one way.

your oil filter is under the front end you have to move engine splash shield.under the front bumper.

connect Heavy Duty jumper cables from battery of a running car to the battery of your TT making sure you get polarities right way round hold the running car in neutral at 2000-3000 RPM for a couple of mins then try starting TT

the oil filter is on the back passanger side just below the turbo the pipes from the oil cooler run into the filter housing