After I put the key on the ignition and switch it to on position I hear this long beep coming from the engine area. most likely from the first picture attached.

secondly, I noticed this leak in the reservoir (see pic 2 and 3). I wipe it clean and next day I see the same. If you look carefully you'll see the reservoir edge has decayed a bit. maybe that's where the fluid is leaking from? I take this is brake oil reservoir?

Also the car is having very rough idle. stalled a few times yesterday when stopped at traffic lights. can it be because I switched fuel type? (went 87 from 89 as I didn't have a choice)

please let me know what you guys think. Appreciate the input.

 

the long beeping noise is your throttle aligning itself. it is normal to hear that sound, but im not positive if it should do it ever time you start it up. knowing the engine/year would help, but from the looks of it it is a ndbw 1.8.

that certainly looks like the brake fluid resevoir, which im my opinion needs to be fixed asap. that is a system that you dont wanna loose pressure in.

i would assume running 87 would be casuing your problems. most people will tell you running one tank of 87 isnt going to hurt too much, but you need to get premium in there next time. and by the way, the recomenned gas is minimum 91, not 89.

 

this is a 1999 A4 1.8 automatic. I'll give you a bit of the recent history so that you can recommend better.

I just made a 350 mile(one way) drive to another state (visiting family), before I drove off I checked the oil level and it was pretty low. added 1 quart and the dipstick oil level was somewhere in the middle. after driving halfway I checked the oil level and it was low again, so I added another quart, checked the oil level and looked full. made it to my destination on friday. I spent my saturday trying to get that ebay vag-com cable to work with no luck. somewhere in their instruction it says if you can't get the cable to work then take the negative terminal of the battery off and try again. so I took it off for a few minutes, still no luck. Later that day I filled up the tank with 87 grade fuel.

That was the recent history. today (sunday) when I started the car, it had very bad idle. the rpm was below 1000 and was going down and back up again, it kept on doing that and the engine would stop in the traffic light. I was having to use my left foot on the brake and right on gas to keep the rpm above 1k.

I think I see some oil leaks ( no oil when I park) in some part of the engine as it's got some oil and dirt there. The car struggles very badly when going uphill, and I also smell burnt oil sometimes.

How do you suggest I fix the brake oil reservoir?

 

Dont know about the oil leaks, but it sounds like the throttle body could be going bad.