I brought an Audi A4 2010 a couple months ago and I'm starting to realize that I have a real engine oil problem (at least I think it is). The car has 80,000 miles on it and it runs actually smooth in my opinion. I have notice that I have to change the engine oil quite frequently. I do have to admit I haven't been using your European syndetic engine oil until now 0w-40 mobile 1. I also have to admit that I was using grade 91 gas instead of 93 gas.

The engine light stay on for a couple of days usually when I'm below 100miles to empty on gas tank than after a few days it will go off than come back on it. I started to assume that this might be because of me changing the grade of gas a little to many times with a certain period of time but than I also started to think maybe there is something wrong with my engine in general.

I have quite a few questions and wondering if the Audi community can answer them for me so I can have a clear head and see what I might be dealing with here:

What does my situation sound like it might be ?

I do not have a warranty is there any possible way I can purchase another warranty from Audi (I have never had a warranty with this car) ?

how much is a diagnostic tests from the Audi dealership out-of-pocket ?

how much is a oil consumption test out of pocket ?

how much would it cost to fix the ring and Pistons on the engine out of pocket ?

How much is a Audi A4 2010 engine out of pocket ?

how much is the labor out-of-pocket to install a Audi a4 engine out of pocket ?

Can you put in more than 1 quart of oil in a Audi engine ? I'm asking because when the engine oil light comes on it say "still safe to drive put in 1 qtr as soon as possible" can I put in 4qtr next time ?

And if somehow I can get a warranty from Audi how much would it usually cost for a car that had 80,000 miles on it if anyone knows off the top of there head ?

In your honest opinion is it just better to buy a whole a lot of engine oil and put in my engine whatever is needed or just buy a whole new engine or use engine completely if I Audi fines that there is a problem ?

I just put in 1qt of engine oil in my car how many miles should it take for my Audi to tell me that it needs more engine oil just wondering ?

Thank you for your feedback, it will be much appreciated thank you