I just put ~11 liters of Petrol in a Audi Q7 2008 with a tank capacity of 80l, I immediately filled it up with diesel and drove about 10 km to my hotel. Some sources say it’s fine if I keep topping it up, others say I’m screwed. Am I ok? Should I add oil?
Do not drive it at all!
Honestly, it’s likely fucked already but driving it more will ensure that. Gas is dry and will cause the high pressure pump to shed small slivers of metal that scatter through the injectors and lines. It was already a common failure on VAG diesels.
I’ve worked on many diesels that got filled with gas and the ones that get driven, even a little, have a near 100% fail rate.
It will be fine. Not ideal, avoid prolonged heavy throttle until you’ve burned a few tanks.
Don’t drive it hard. Top off with diesel often. Should be okay once you run a couple tanks through it. Change the fuel filter too.
It will be fine a 3l of petrol in a tank of diesel is perfectly fine it will act as a anti gel agent in cold weather. 11l is a bit much and will essentially float on the diesel, so your car will run fine until you get low in fuel.
The petrol acts as a solvent and thins the lubricants in the diesel, so the engine runs hotter.
So fill up at 1/2 a tank and run a few tanks through it and you will be fine.
Drain, flush and refill. Or risk big bucks on Pump and injector damage
Your Q7 has the common rail fuel system. That fuel system is VERY VERY weak and is highly susceptible to damage from misfueling.
The general consensus is that anything more than 2% contamination has a high risk of high pressure fuel pump destruction.
11 liters of an 80 liter tank is 13%. Do not drive your vehicle again. You need to drain the fuel tank and all of the fuel lines, flush them completely with diesel and a fuel lubricant improver, then pray to what ever diety you believe in.